SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 8-K Current Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported) April 1, 2003 ------------------------ UNOCAL CORPORATION -------------------------------------------------------------------------------- (Exact name of registrant as specified in its charter) Delaware -------------------------------------------------------------------------------- (State or Other Jurisdiction of Incorporation) 1-8483 95-3825062 -------------------------------------------------------------------------------- (Commission File Number) (I.R.S. Employer Identification No.) 2141 Rosecrans Avenue, Suite 4000, El Segundo, California 90245 -------------------------------------------------------------------------------- (Address of Principal Executive Offices) (Zip Code) (310) 726-7600 -------------------------------------------------------------------------------- (Registrant's Telephone Number, Including Area Code) Item 5. Other Events. The Rights Agreement, dated as of January 5, 2000, between Unocal Corporation, and Mellon Investor Services LLC, as rights agent, has been amended effective April 1, 2003. The amendment is filed as an exhibit under Item 7(c) of this report. Item 7. Financial Statements and Exhibits. (c) Exhibits 10. Amendment to Rights Agreement, dated as of April 1, 2003, between Unocal Corporation and Mellon Investor Services LLC. Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. UNOCAL CORPORATION (Registrant) Date: April 2, 2003 By: /s/ JOE D. CECIL ------------------ ------------------------------- Joe D. Cecil Vice President and Comptroller -1-