As filed with the Securities and Exchange Commission on June 8, 2004
                              Registration No. 33-


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM S-8


                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933


                              IONICS, INCORPORATED
             (Exact name of registrant as specified in its charter)


         Massachusetts                                 04-2068530
(State or other jurisdiction of            (IRS employer identification number)
 incorporation or organization)


                                 65 Grove Street
                       Watertown, Massachusetts 02472-2882
              (Address and zip code of principal executive offices)


                 INDUCEMENT NON-QUALIFIED STOCK OPTION AGREEMENT
                            (Full title of the Plan)


                               Stephen Korn, Esq.
                        Vice President & General Counsel
                              Ionics, Incorporated
                                 65 Grove Street
                       Watertown, Massachusetts 02472-2882
                     (Name and address of agent for service)

                                  617-926-2500
          (Telephone number, including area code, of agent for service)








                         CALCULATION OF REGISTRATION FEE

                                                                  Proposed           Proposed
                                                                   Maximum            Maximum
                                            Amount to be       Offering Price        Aggregate            Amount of
 Title of Securities to be Registered      Registered (1)         Per Share       Offering Price      Registration Fee
 ------------------------------------      --------------         ---------       --------------      ----------------

                                                                                               
Common Stock (Par Value $1.00 Per
Share)                                         150,000             $23.07           $3,460,500             $439.02

Total                                          150,000             $23.07           $3,460,500             $439.02
---------------


(1)      Pursuant to Rule 416(a) under the Securities Act of 1933, this
         Registration Statement shall also cover any additional shares of Common
         Stock which become issuable upon exercise of options granted under the
         Inducement Non-Qualified Stock Option Agreement by reason of any stock
         dividend, stock split, recapitalization or other similar transaction.



                                      -2-



                                     PART I


Item 1.    Plan Information

          The documents containing the information specified in this Item 1 will
          be sent or given to the Vice President,  Americas Sales and Marketing,
          Water  Systems  Division  of the  Registrant,  to whom the  Inducement
          Non-Qualified Stock Option Agreement was granted on April 30, 2004, as
          specified  by Rule  428(b)  (1).  In  accordance  with the  rules  and
          regulations   of  the   Securities   and  Exchange   Commission   (the
          "Commission") and the instructions to Form S-8, such documents are not
          being filed with the  Commission  either as part of this  Registration
          Statement or as  prospectuses  or prospectus  supplements  pursuant to
          Rule 424.

Item 2.    Registrant Information and Employee Plan Annual Information

           The documents containing the information specified in this Item 2
           will be sent or given to the Vice President, Americas Sales and
           Marketing, Water Systems Division as specified by Rule 428(b) (1). In
           accordance with the rules and regulations of the Commission and the
           instructions to Form S-8, such documents are not being filed with the
           Commission either as part of this Registration Statement or as
           prospectuses or prospectus supplements pursuant to Rule 424.


                                     PART II


               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.    Incorporation of Documents by Reference

          The following  documents filed with the Commission are incorporated by
          reference in this Prospectus:

          (a)  The Annual  Report of the  Registrant on Form 10-K for the fiscal
               year ended December 31, 2003,  filed with the Commission on March
               15, 2004  pursuant to the  Securities  Exchange  Act of 1934,  as
               amended,  which  contains  audited  financial  statements  of the
               Registrant for the fiscal year ended December 31, 2003.

          (b)  The  Quarterly  Report  of the  Registrant  on Form  10-Q for the
               fiscal quarter ended March 31, 2004, filed with the Commission on
               May 10, 2004 pursuant to the Securities  Exchange Act of 1934, as
               amended.

          (c)  The section entitled  "Description of Registrant's  Securities to
               be  Registered"   contained  in  the  Registrant's   Registration
               Statement on Form 8-A, filed with the Commission on September 27,
               1990 pursuant to Section 12(g) of the Exchange Act, including any
               amendments  or reports  that have been  filed for the  purpose of
               updating this description.

               All  documents  subsequently  filed  with the  Commission  by the
               Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the
               Exchange Act, prior to the filing of a  post-effective  amendment
               which indicates that all securities offered herein have been sold
               or which deregisters all securities then remaining unsold,  shall
               be deemed to be  incorporated  by reference in this  Registration
               Statement  and to be a part  hereof  from the date of filing such
               documents.

Item 4.    Description of Securities

           Not applicable.


                                      -3-



Item 5.    Interest of Named Experts and Counsel

           The validity of the shares of Common Stock offered hereby will be
           passed upon for the Registrant by Stephen Korn, Esq., Vice President
           and General Counsel of the Registrant. Mr. Korn is the beneficial
           owner of 135,356 shares of Common Stock, including 132,500 shares of
           Common Stock in the form of presently exercisable stock options and
           1,633 shares held in the Ionics Section 401(k) Savings Plan (based on
           May 24, 2004 data).

Item 6.    Indemnification of Directors and Officers

           The Registrant is permitted by Massachusetts law and required by its
           By-laws to indemnify any director or officer or former director or
           officer against all expenses and liabilities reasonably incurred by
           him in connection with any legal action in which such person is
           involved by reason of his position with the Registrant unless he
           shall have been finally adjudicated in any action, suit or proceeding
           not to have acted in good faith in the reasonable belief that his
           action was in the best interests of the Registrant. Such
           indemnification shall include payment by the Registrant of expenses
           incurred in defending a civil or criminal action or proceeding in
           advance of the final disposition of such action or proceeding, upon
           the Registrant's receipt of the undertaking of the person indemnified
           to repay such payment if such person shall be adjudicated not
           entitled to such indemnification.

           Directors and officers are also insured up to an aggregate amount of
           $20 million under Directors' and Officers' Liability and Company
           Reimbursement Policies.

           The Registrant's Restated Articles of Organization include a
           provision limiting the personal liability of directors of the Company
           to its stockholders for monetary damages for breaches of their
           fiduciary duty to the extent permitted by the Massachusetts Business
           Corporation Law.

Item 7.    Exemption from Registration Claimed

           Not applicable.

Item 8.    Exhibits

Exhibit No.  Description of Exhibit
-----------  ----------------------

  4.1        Renewed Rights Agreement, dated as of August 19, 1997,           *
             between the Registrant and BankBoston N.A. (filed as Exhibit
             1 to the Registrant's Current Report on Form 8-K dated
             August 27, 1997).

  4.2        Amendment No. 1 dated as of November 17, 2003, to the            *
             Renewed Rights Agreement dated August 19, 1997 between
             the Registrant and Equiserve Trust Company as Rights Agent
             (and successor in interest to BankBoston N.A.)
             (filed as Exhibit 4.1 to the Registrant's Current Report on
             Form 8-K dated November 26, 2003.)

  4.3        Form of Common Stock Certificate (filed as Exhibit 4.2 to the    *
             Registrant's Annual Report on Form 10-K for the year ended
             December 31, 1995).

  4.4        Inducement Non-Qualified Stock Option Agreement between the      9
             Registrant and Lester B. Devitt dated April 30, 2004.

  5.1        Opinion of Stephen Korn, General Counsel (filed herewith).      15

 23.1        Consent of PricewaterhouseCoopers LLP (filed herewith).         16

 23.2        Consent of KPMG LLP (filed herewith).                           17


                                      -4-


 23.3        Consent of Stephen Korn, General Counsel (included in
             Exhibit 5.1).                                                   15

 24          Power of Attorney (included as part of the signature page of
             this Registration Statement).                                    7
--------------------------
*Incorporated herein by reference.

Item 9.    Undertakings

(a)  The undersigned Registrant hereby undertakes:

     (1)  To file,  during any period in which offers or sales are being made, a
          post-effective amendment to this Registration Statement:

          (i)  To include any  prospectus  required  by Section  10(a)(3) of the
               Securities Act of 1933;

          (ii) To reflect in the  prospectus  any facts or events  arising after
               the  effective  date of the  Registration  Statement (or the most
               recent post-effective  amendment thereof) which,  individually or
               in  the  aggregate,   represents  a  fundamental  change  in  the
               information set forth in the Registration Statement;

          (iii)To include any material  information  with respect to the plan of
               distribution   not  previously   disclosed  in  the  Registration
               Statement  or any  material  change  to such  information  in the
               Registration Statement;

               Provided,  however,  that paragraphs  (a)(1)(i) and (a)(1)(ii) do
               not apply if the  Registration  Statement  is on Form S-3 or Form
               S-8  and  the   information   required   to  be   included  in  a
               post-effective  amendment  by those  paragraphs  is  contained in
               periodic reports filed with or furnished to the Commission by the
               Registrant  pursuant  to  Section  13 or  Section  15(d)  of  the
               Securities   Exchange  Act  of  1934  that  are  incorporated  by
               reference in the Registration Statement.

     (2)  That,  for  the  purpose  of  determining   any  liability  under  the
          Securities Act of 1933,  each such  post-effective  amendment shall be
          deemed to be a new registration  statement  relating to the securities
          offered  therein,  and the  offering of such  securities  at that time
          shall be deemed to be the initial bona fide offering thereof.

     (3)  To remove from registration by means of a post-effective amendment any
          of  the  securities  being  registered  which  remain  unsold  at  the
          termination of the offering.

(b)  The  undersigned   Registrant  hereby  undertakes  that,  for  purposes  of
     determining  any liability under the Securities Act of 1933, each filing of
     the  Registrant's  annual report  pursuant to Section 13(a) or 15(d) of the
     Securities  Exchange Act of 1934 (and, where applicable,  each filing of an
     employee  benefit  plan's  annual  report  pursuant to Section 15(d) of the
     Securities  Exchange Act of 1934) that is  incorporated by reference in the
     Registration  Statement shall be deemed to be a new registration  statement
     relating  to the  securities  offered  therein,  and the  offering  of such
     securities  at that  time  shall be  deemed  to be the  initial  bona  fide
     offering thereof.

(c)  Insofar as indemnification for liabilities arising under the Securities Act
     of 1933 may be permitted to directors, officers, and controlling persons of
     the  Registrant  pursuant to the foregoing  provisions,  or otherwise,  the
     Registrant  has been  advised  that in the  opinion of the  Securities  and
     Exchange  Commission  such  indemnification  is  against  public  policy as
     expressed in the Act, and is, therefore, unenforceable. In the event that a
     claim for indemnification  against such liabilities (other than the payment
     by the Registrant of expenses incurred or paid by a director,  officer,  or
     controlling  person of the  Registrant  in the  successful  defense  of any
     action,  suit, or  proceeding) is asserted by such  director,  officer,  or
     controlling person in connection with the securities being registered,  the
     Registrant  will,  unless in the opinion of its counsel the matter has been
     settled  by  controlling  precedent,  submit  to  a  court  of  appropriate
     jurisdiction  the question  whether such  indemnification  by it is against
     public  policy as  expressed  in the Act and will be  governed by the final
     adjudication of such issue.


                                      -5-


                                   SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the Town of Watertown and Commonwealth of Massachusetts on the
7th day of June, 2004.

                                            IONICS, INCORPORATED


                                            By: /s/Douglas R. Brown
                                                ----------------------------
                                                Douglas R. Brown
                                                President and
                                                Chief Executive Officer


                                      -6-



                        POWER OF ATTORNEY AND SIGNATURES

Each person whose signature appears below on this Registration Statement hereby
constitutes and appoints Douglas R. Brown and Stephen Korn and each of them,
with full power to act without the other, his true and lawful attorney-in-fact
and agent, with full power of substitution and resubstitution, for him and in
his name, place and stead, in any and all capacities (until revoked in writing)
to sign any and all amendments (including post-effective amendments and
amendments thereto) to this Registration Statement of Ionics, Incorporated, and
to file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting unto said
attorneys-in-fact and agents, and each of them, full power and authority to do
and perform each and every act and thing requisite and necessary fully to all
intents and purposes as he or she might or could do in person thereby ratifying
and confirming all that said attorneys-in-fact and agents or any of them, or
their or his substitute or substitutes, may lawfully do or cause to be done by
virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration
Statement has been signed below by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated.



           Signature                                       Title                                  Date

                                                                                        
/s/Douglas R. Brown                        President and Chief Executive Officer              June 7, 2004
--------------------------------
Douglas R. Brown                               (Principal Executive Officer)

/s/Daniel M. Kuzmak                     Vice President and Chief Financial Officer            June 7, 2004
--------------------------------
Daniel M. Kuzmak                               (Principal Financial Officer)

/s/Anthony Di Paola                       Vice President and Corporate Controller             June 7, 2004
--------------------------------
Anthony Di Paola                              (Principal Accounting Officer)

/s/Stephen L. Brown                         Chairman of the Board and Director                June 7, 2004
--------------------------------
Stephen L. Brown

/s/Lyman B. Dickerson               Vice President, Water Systems Division and Director       June 7, 2004
--------------------------------
Lyman B. Dickerson

/s/Kathleen F. Feldstein                                 Director                             June 7, 2004
--------------------------------
Kathleen F. Feldstein

/s/William K. Reilly                                     Director                             June 7, 2004
--------------------------------
William K. Reilly

/s/John J. Shields                                       Director                             June 7, 2004
--------------------------------
John H. Shields

/s/Frederick T. Stant, III                               Director                             June 7, 2004
--------------------------------
Frederick T. Stant

/s/Robert H. Temkin                                      Director                             June 7, 2004
--------------------------------
Robert H. Temkin

/s/Daniel I. C. Wang                                     Director                             June 7, 2004
--------------------------------
Daniel I. C. Wang

/s/Mark S. Wrighton                                      Director                             June 7, 2004
--------------------------------
Mark S. Wrighton

/s/Allen S. Wyett                                        Director                             June 7, 2004
--------------------------------
Allen S. Wyett


                                      -7-



                                  EXHIBIT INDEX



                                                                                     Sequentially Numbered
  Exhibit No.                         Description of Exhibits                                 Page

                                                                                          
4.1              Renewed Rights Agreement, dated as of August 19, 1997, between                 *
                 the Registrant and BankBoston N.A. (filed as Exhibit 1 to the
                 Registrant's Current Report on Form 8-K dated August 27, 1997).

4.2              Amendment No. 1 dated as of November 17, 2003, to the Renewed                  *
                 Rights Agreement dated August 19, 1997 between the Registrant and
                 EquiServe Trust Company as Rights Agent (and successor in
                 interest to BankBoston N.A.) (filed as Exhibit 4.1 to the
                 Registrant's Current Report on Form 8-K dated November 26, 2003).

4.3              Form of Common Stock Certificate (filed as Exhibit 4.2 to the                  *
                 Registrant's Annual Report on Form 10-K for the year ended
                 December 31, 1995).

4.4              Inducement Non-Qualified Stock Option Agreement between the                    9
                 Registrant and Lester B. Devitt dated April 30, 2004.

5.1              Opinion of Stephen Korn, General Counsel (filed herewith).                    15

23.1             Consent of PricewaterhouseCoopers LLP (filed herewith).                       16

23.2             Consent of KPMG LLP (filed herewith).                                         17

23.3             Consent of Stephen Korn, General Counsel (included in Exhibit
                 5.1).                                                                         15

24               Power of Attorney (included as part of the signature page of this
                 Registration Statement).                                                       7

*Incorporated herein by reference.


                                      -8-




                                                                     EXHIBIT 4.4

                              IONICS, INCORPORATED

                 Inducement Non-Qualified Stock Option Agreement

         This Inducement Non-Qualified Stock Option Agreement (the "Agreement")
made as of April 30, 2004 (the "Date of Grant") by and between Ionics,
Incorporated, a Massachusetts corporation (the "Company"), and Lester B. Devitt
(the "Employee"):

         1. Option Grant. The Company hereby grants as of the Date of Grant to
the Employee an option to purchase a maximum of 150,000 shares (the "Option
Shares") of its common stock, $1.00 par value ("Common Stock"), at the price of
$23.07 per share, on the terms and conditions set forth in this Agreement.

         2. Grant as Non-Qualified Option; Other Options. This option shall be
treated for federal income tax purposes as a Non-Qualified Option (rather than
an incentive stock option). This option is in addition to any other options
heretofore or hereafter granted to the Employee by the Company or any present or
future parent or subsidiary of the Company (such parents or subsidiaries
referred to collectively as the "Related Corporations"), but a duplicate
original of this instrument shall not effect the grant of another option.

         3. Vesting of Option if Employment Continues. If the Employee has
continued to serve the Company or any Related Corporation in the capacity of an
employee, officer or consultant, as the case may be (such service is described
herein as maintaining or being "employed by the Company") on the following
dates, the Employee may exercise this option at any time from and after the
applicable date for the number of shares of Common Stock set forth opposite the
applicable date:

         Applicable Date                       Shares

         Date of Grant                         37,500 shares
         First Anniversary of Date of Grant    an additional 37,500 shares
         Second Anniversary of Date of Grant   an additional 37,500 shares
         Third Anniversary of Date of Grant    an additional 37,500 shares

         Notwithstanding the foregoing, (i) if the Employee's employment with
the Company is terminated by the Company for any reason other than for Cause (as
defined in Section 4(b) hereof), or by reason of the Employee's death or
Permanent Disability (as defined in Section 5(b) hereof, the Employee shall be
deemed for purposes of this Section 3 to have remained employed by the Company
for 12 months after such termination, and any shares that would have become
exercisable during such 12-month period shall become exercisable immediately
prior to such termination of the Employee's employment with the Company; and
(ii) if the Employee's employment with the Company is terminated by the Company
for Cause, no further shares shall become exercisable from and after such
termination of the Employee's employment with the Company.

                  Notwithstanding the foregoing, the Compensation Committee of
           the Company's Board of Directors (the "Committee") may, in its
           discretion, accelerate the date that any installment of this option
           becomes exercisable. The foregoing rights are cumulative and (subject
           to Sections 3 or 4 hereof if the Employee ceases to be employed by
           the Company and all Related Corporations), may be exercised up to and
           including the date that is ten years from the date this option is
           granted (the "Scheduled Expiration Date").

         4. Termination of Employment Relationship.

                  (a) Termination Other than for Cause. If the Employee's
employment with the Company is terminated by the Employee or by the Company,
other than by reason of Cause, this option may be exercised, to the extent
otherwise exercisable on the date of his termination (including any portions of
this option that become exercisable on or before his termination in accordance
with Section 3), at any time prior the Scheduled Expiration Date. In such case,
the Employee's only rights hereunder shall be those which are properly exercised
before the termination of this option.

                                      -9-


                  (b) Termination for Cause. If the Employee's employment with
the Company is terminated by the Company for Cause, all vested options will be
forfeited and this option shall terminate upon the Employee's receipt of written
notice of such termination and shall thereafter not be exercisable to any extent
whatsoever. For purposes of the Agreement, "Cause" shall mean any of the
following: (i) the Employee's dishonesty, malfeasance, disloyalty or breach of
fiduciary duties to the Corporation; (ii) the conviction of, or plea of guilty
or nolo contendere by, the Employee for any felony involving moral turpitude (or
for any lesser crime or offense involving the Corporation); (iii) the failure or
refusal, except due to incapacity as a result of illness or disability, of the
Employee to perform the lawful duties appropriate to his office assigned to him,
provided that such failure or refusal continues uncorrected for a period of 30
days after the Employee shall have received specific written directions in
respect thereof from his immediate supervisor; or (iv) any breach by the
Employee of the Employer's Agreement With Employee dated March 17, 2004.

         5.       Death; Disability.

                  (a) Death. If the Employee dies while employed by the Company,
  this option may be exercised, to the extent otherwise exercisable on the date
  of his death (including any portions of this option that become exercisable on
  or before his termination in accordance with Section 3), by the Employee's
  estate, personal representative or beneficiary to whom this option has been
  assigned pursuant to Section 9, at any time prior to the Scheduled Expiration
  Date.

                   (b) Disability. If the Employee's employment with the Company
is terminated by reason of his Permanent Disability, this option may be
exercised, to the extent otherwise exercisable on the date employment was
terminated (including any portions of this option that become exercisable on or
before his termination in accordance with Section 3), at any time prior to the
Scheduled Expiration Date. For purposes of this Agreement, "Permanent
Disability" shall mean the Employee's inability, by reason of any physical or
mental impairment, to substantially perform the significant aspects of his
regular duties, which inability is reasonably contemplated to continue for at
least one (1) year from its incidence and at least 90 days from the date of such
determination. Any question as to the existence, extent, or potentiality of the
Employee's Permanent Disability shall be determined by a qualified independent
physician selected by the Employee (or, if the Employee is unable to make such
selection, by an adult member of the Employee's immediate family) and reasonably
acceptable to the Board.


         5.       Death; Disability.

               (a)  Death.  If the Employee dies while  employed by the Company,
                    this  option  may  be  exercised,  to the  extent  otherwise
                    exercisable on the date of his death (including any portions
                    of this  option  that  become  exercisable  on or before his
                    termination in accordance with Section 3), by the Employee's
                    estate,  personal representative or beneficiary to whom this
                    option has been assigned  pursuant to Section 9, at any time
                    prior to the Scheduled Expiration Date.

               (b)  Disability. If the Employee's employment with the Company is
                    terminated  by  reason  of his  Permanent  Disability,  this
                    option may be exercised, to the extent otherwise exercisable
                    on  the  date  employment  was  terminated   (including  any
                    portions of this option that become exercisable on or before
                    his  termination in accordance  with Section 3), at any time
                    prior to the Scheduled Expiration Date.

         6. Partial Exercise. This option may be exercised in part at any time
and from time to time within the above limits, except that this option may not
be exercised for a fraction of a share.

         7. Payment of Price.

                  (a) Form of Payment. The option price shall be paid in the
following manner:

                    (i)  in cash or by check;

                                      -10-


                    (ii) subject to Section 7(b) below, by delivery of shares of
                         the  Company's  Common Stock having a fair market value
                         (as determined by the  Committee)  equal as of the date
                         of exercise to the option price;

                    (iii)by delivery of an assignment  satisfactory  in form and
                         substance to the Company of a sufficient  amount of the
                         proceeds  from the  sale of the  Option  Shares  and an
                         instruction  to the broker or selling agent to pay that
                         amount to the Company; or

                    (iv) by any combination of the foregoing.

                  (b) Limitations on Payment by Delivery of Common Stock. If the
Employee delivers Common Stock held by the Employee ("Old Stock") to the Company
in full or partial payment of the option price, and the Old Stock so delivered
is subject to restrictions or limitations imposed by agreement between the
Employee and the Company, an equivalent number of Option Shares shall be subject
to all restrictions and limitations applicable to the Old Stock to the extent
that the Employee paid for the Option Shares by delivery of Old Stock, in
addition to any restrictions or limitations imposed by this Agreement.
Notwithstanding the foregoing, the Employee may not pay any part of the exercise
price hereof by transferring Common Stock to the Company unless such Common
Stock has been owned by the Employee free of any substantial risk of forfeiture
for at least six months.

         8. Restrictions of Transfer; Legend. Unless registered pursuant to the
provisions of the Securities Act of 1933, as amended (the "Securities Act"),
Option Shares may not be transferred without the Company's written consent
except by will, or by the laws of descent and distribution. Option Shares will
be of an illiquid nature and will be deemed to be "restricted securities" for
purposes of the Securities Act, unless registered. Accordingly, such shares must
be sold in compliance with the registration requirements of the Securities Act
or an exemption therefrom.

         9. Method of Exercising Option. Subject to the terms and conditions of
this Agreement, this option may be exercised by written notice to the Company,
at the principal executive office of the Company, in the form of Exhibit A
annexed hereto. Such notice shall state the election to exercise this option and
the number of Option Shares for which it is being exercised and shall be signed
by the person or persons so exercising this option. Such notice shall be
accompanied by payment of the full purchase price of such shares (unless payment
is being made pursuant to Section 7(a)(iii) hereof), and the Company shall
deliver a certificate or certificates representing such shares as soon as
practicable after the notice shall be received. Such certificate or certificates
shall be registered in the name of the person or persons so exercising this
option (or, if this option shall be exercised by the Employee and if the
Employee shall so request in the notice exercising this option, shall be
registered in the name of the Employee and another person jointly, with right of
survivorship). In the event this option shall be exercised, pursuant to Section
5 hereof, by any person or persons other than the Employee, such notice shall be
accompanied by appropriate proof of the right of such person or persons to
exercise this option.

         10. Transferability of Option. This option may be transferred by the
Employee to (i) the spouse, children, or grandchildren of the Employee
("Immediate Family Members"); (ii) a trust or trusts for the exclusive benefit
of the Employee or the Immediate Family Members; or (iii) a partnership, limited
liability company, corporation or other entity in which the Employee or the
Immediate Family Members are the only partners, members, or stockholders. Any
subsequent transfer of this option shall be prohibited other than by will or the
laws of descent and distribution.

         11. No Obligation to Exercise Option. The grant and acceptance of this
option imposes no obligation on the Employee to exercise it.

         12. No Obligation to Continue Employment. Neither this Agreement nor
the grant of this option imposes any obligation on the Company or any Related
Corporation to continue to employ the Employee.

         13. No Rights as Stockholder until Exercise. The Employee shall have no
rights as a stockholder with respect to the Option Shares until such time as the
Employee has exercised this option by delivered a notice of exercise and has
paid in full the purchase price for the number of shares for which this option
is to be so exercised in accordance with Section 8. No adjustment shall be made
for dividends or similar rights for which the record date is prior to such date
of exercise.


                                      -11-


         14. Adjustments Upon Changes in Capitalization and Other Events. Upon
the occurrence of any of the following events, an Employee's rights with respect
to this option shall be adjusted as hereinafter provided:

                  (a) Stock Dividends and Stock Splits. If the shares of Common
Stock shall be subdivided or combined into a greater or smaller number of shares
or if the Company shall issue any shares of Common Stock as a stock dividend on
its outstanding Common Stock, the number of shares of Common Stock deliverable
upon the exercise of this option shall be appropriately increased or decreased
proportionately, and appropriate adjustments shall be made in the purchase price
per share to reflect such subdivision, combination or stock dividend.

                  (b) Recapitalization Adjustments. Immediately upon the
consummation of an Acquisition (as defined below), this option shall immediately
become fully exercisable and shall remain the obligation of the Company or be
assumed by the surviving or acquiring entity, and there shall automatically be
substituted for the shares of Common Stock subject to this option, the
consideration payable with respect to the outstanding shares of Common Stock in
connection with the Acquisition. In the event of a reorganization,
recapitalization, merger, consolidation, or any other change in the corporate
structure or shares of the Company, adjustments in the number and kind of shares
covered by, and in the exercise price of, this option necessary to maintain the
proportionate interest of the Employee and preserve, without exceeding, the
value of this option, shall be made. For purposes of this Section 14, an
"Acquisition" shall mean: (x) any merger, consolidation or purchase of
outstanding capital stock of the Company, or other form of business combination
in which the Company is the target of such combination or after which the voting
securities of the Company outstanding immediately prior thereto represent
(either by remaining outstanding or by being converted into voting securities of
the surviving or acquiring entity) less than 50% of the combined voting power of
the voting securities of the Company or such surviving or acquiring entity
outstanding immediately after such event (other than as a result of a financing
transaction); or (y) any sale of all or substantially all of the capital stock
or assets of the Company in a business combination (other than in a spin-off or
similar transaction); or (z) any other acquisition of the business of the
Company, as determined by the Committee.

                  (c) Issuance of Securities. Except as expressly provided
herein, no issuance by the Company of shares of stock of any class, or
securities convertible into shares of stock of any class, shall affect, and no
adjustment by reason thereof shall be made with respect to, the number or price
of shares subject to this option. No adjustments shall be made for dividends
paid in cash or in property other than securities of the Company.

                  (d) Adjustments. Upon the happening of any of the foregoing
events, the class and aggregate number of shares that are subject to this option
shall be appropriately adjusted to reflect such events. The Committee shall
determine the specific adjustments to be made under this Section 14 and its
determination shall be conclusive.

         15. Withholding Taxes. If the Company or any Related Corporation in its
discretion determines that it is obligated to withhold any tax in connection
with the exercise of this option, or in connection with the transfer of, or the
lapse of restrictions on, any Common Stock or other property acquired pursuant
to this option, the Employee hereby agrees that the Company or any Related
Corporation may withhold from the Employee's wages or other remuneration the
appropriate amount of tax. At the discretion of the Company or Related
Corporation, the amount required to be withheld may be withheld in cash from
such wages or other remuneration or in kind from the Common Stock or another
property otherwise deliverable to the Employee on exercise of this option. The
Employee further agrees that, if the Company or Related Corporation does not
withhold an amount from the Employee's wages or other remuneration sufficient to
satisfy the withholding obligation of the Company or Related Corporation, the
Employee will make reimbursement on demand, in cash, for the amount withheld.

          16. Employee Not to Compete. The Employee acknowledges that he is
  subject to certain non-competition obligations set forth in the Agreement with
  Employee between the Employee and the Company dated March 17, 2004.

         17. Provision of Documentation to Employee. By signing this Agreement
the Employee acknowledges receipt of a copy of this Agreement.

         18.      Miscellaneous.

                  (a) Notices. All notices hereunder shall be in writing and
shall be deemed given when sent by certified or registered mail, postage
prepaid, return receipt requested, to the address et forth below. The addresses


                                      -12-


or such notices may be changed from time to time by written notice given in the
manner provided for herein.

                  (b) Entire Agreement; Modification. This Agreement constitutes
the entire agreement between the parties relative to the subject matter hereof,
and supersedes all proposals, written or oral, and all other communications
between the parties relating to the subject matter of this Agreement. This
Agreement may be modified, amended or rescinded only by a written agreement
executed by both parties.

                  (c) Severability. The invalidity, illegality or
unenforceability of any provision of this Agreement shall in no way affect the
validity, legality or enforceability or of any other provisions.

                  (d) Successors and Assigns. This Agreement shall be binding
upon and inure to the benefit of the parties hereto and their respective
successors and assigns, subject to the limitations set forth in Section 10
hereof.
                  (e) Governing Law. This Agreement shall be governed by and
interpreted in accordance with the laws of the Commonwealth of Massachusetts,
without giving effect to the principles of the conflicts of laws thereof. The
preceding choice of law provisions shall apply to all claims, under any theory
whatsoever, arising out of the relationship of the parties contemplated herein.

         IN WITNESS WHEREOF, the Company and the Employee have caused this
instrument to be executed as of the date first above written.

                                          IONICS, INCORPORATED



/s/Lester B. Devitt                       By: /s/Douglas R. Brown
-----------------------                       -----------------------------
Employee                                      Douglas R. Brown
                                              Chief Executive Officer

Lester B. Devitt
----------------
Print Name of Employee
Address:

                                      -13-



                                                                      EXHIBIT A


Ionics, Incorporated
65 Grove Street
Watertown, MA  02472

Attention:  Assistant Treasurer

Gentlemen:

Please take notice that the undersigned hereby elects to exercise the stock
option granted to Lester B. Devitt on April 30, 2004 by and to the extent of
purchasing __________ shares of the Common Stock of Ionics, Incorporated (the
"Company") for the option price of $23.07 per share, subject to the terms and
conditions of the Inducement Non-Qualified Stock Option Agreement dated as of
April 30, 2004 by and between the Company and Lester B. Devitt (the
"Agreement").

The undersigned hereby agrees to make payment, in cash or in such other property
as permitted under the Agreement, of the purchase price for said shares for
delivery to the undersigned of the stock certificate of the Company representing
the shares purchased, pursuant to Section 7 of the Agreement. If the undersigned
is making payment of any part of the purchase price by delivery of shares of
Common Stock of the Company, the undersigned hereby confirms that he has
investigated and considered the possible income tax consequences to the
undersigned of making such payments in said form, and also confirms that he has
owned such Common Stock free of any substantial risk of forfeiture for at least
six months.

The undersigned hereby specifically confirms to the Company that, unless the
Company has effected the registration with the U.S. Securities and Exchange
Commission of the shares of Common Stock to be issued pursuant to this exercise,
the undersigned is acquiring said shares for investment and not with a view to
sale or distribution thereof. The undersigned further confirms that said shares
shall be held subject to all of the terms and conditions and the Agreement.

                        Very truly yours,


                        -------------------------------

                        Signed by ______________________
                         (party duly exercising option)


                                      -14-



                                                                     EXHIBIT 5.1
June 7, 2004

Ionics, Incorporated
65 Grove Street
Watertown, Massachusetts 02472-2882

Re: Registration Statement on Form S-8 relating to an Inducement Non-Qualified
    Stock Option Agreement

Ladies and Gentlemen:

As General Counsel for Ionics, Incorporated, a Massachusetts corporation (the
"Company"), I am familiar with its corporate affairs. In particular, I have
acted as counsel for the Company in connection with the registration of 150,000
shares of the Company's common stock, par value $1.00 per share (the "Shares"),
reserved for issuance under an Inducement Non-Qualified Stock Option Agreement
between the Company and Lester B. Devitt, its newly appointed Vice President,
Americas Sales and Marketing, Water Systems Division, dated April 30, 2004 (the
"Option") pursuant to a Registration Statement on Form S-8 (the "Registration
Statement") filed by the Company on the date hereof with the Securities and
Exchange Commission under the Securities Act of 1933, as amended, and the
conduct of certain corporate proceedings relating thereto.

As such counsel, I have examined and am familiar with the Registration
Statement, certain corporate records of the Company, including its Restated
Articles of Organization, as amended, its By-Laws, as amended, minutes of
meetings of its Board of Directors and stockholders, and such other documents,
instruments and certificates of government officials as I have deemed necessary
as a basis for the opinions herein expressed.

In my examination described in the preceding paragraph, I have assumed the
genuineness of all signatures, the authenticity of all documents submitted to me
as originals, the conformity to the corresponding originals of all documents
submitted to me as copies, the authenticity of the originals of such copies, and
the accuracy and completeness of all corporate records.

I have made such examination of Massachusetts law as I have deemed relevant for
purposes of this opinion, but have not made any review of the laws of any other
state or jurisdiction. Accordingly, this opinion is limited to Massachusetts
law.

Based upon and subject to the foregoing, I am of the opinion that the Shares to
be issued by the Company from time to time pursuant to the Plan will be duly
authorized, validly issued, fully paid and non-assessable.

I hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and further consent to the use of my name wherever
appearing in the Registration Statement and any amendments thereto. This opinion
is being furnished to you solely for the foregoing use and, other than in
connection with such use, is not to be disseminated, reproduced or published in
any form, used for any other purpose or relied upon by any other person or
entity without my prior written consent.

Very truly yours,

/s/ Stephen Korn
----------------
Stephen Korn
General Counsel

                                      -15-



                                                                   EXHIBIT 23.1


            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM


We hereby consent to the incorporation by reference in this Registration
Statement on Form S-8 of our report dated March 12, 2004, relating to the
financial statements and financial statement schedule of Ionics, Incorporated,
which appears in the Ionics, Incorporated Annual Report on Form 10-K for the
year ended December 31, 2003.



/s/PricewaterhouseCoopers LLP
-----------------------------
PricewaterhouseCoopers LLP
Boston, Massachusetts
June 7, 2004


                                      -16-



                                                                   EXHIBIT 23.2


                       CONSENT OF INDEPENDENT AUDITORS


We consent to the incorporation by reference in this Registration Statement on
Form S-8 of Ionics, Incorporated of our report dated November 3, 2003 with
respect to the combined balance sheets of The Ecolochem Group as of September
30, 2003 and 2002, and the related combined statements of earnings,
stockholders' equity and comprehensive income, and cash flows for each of the
years in the three-year period ended September 30, 2003, which report appears in
the Form 8-K of Ionics, Incorporated filed on February 12, 2004.


/s/KPMG LLP
-----------
KPMG LLP
Norfolk, Virginia
June 7, 2004


                                      -17-