press release

Unocal begins redemption of outstanding trust convertible preferred securities

El Segundo, Calif., Dec. 16, 2004 - Unocal Corporation (NYSE: UCL) today said that Unocal Capital Trust has given notice to the Bank of New York (as trustee) to redeem the remaining outstanding 6-1/4% Trust Convertible Preferred Securities.

The 5.2 million shares expected to be redeemed have an aggregate liquidation value of about $261 million. These securities will be redeemed on Jan. 19, 2005, with a redemption premium of 1.25 percent. Including the premium and accrued and unpaid distributions, the total cost of the redemption program is $266 million, assuming no conversion of any of the preferred securities into common stock prior to the redemption.

The redemption of the trust convertible preferred securities is one aspect of a two-part $465 million cash expenditure program that Unocal announced earlier this month. The other aspect is the repurchase of Unocal's common stock.

About Unocal Corporation

Unocal is one of the world's leading independent natural gas and crude oil exploration and production companies. The company's principal oil and gas activities are in Asia and North America.

This news release contains forward-looking statements about matters such as the consummation, amounts, and timing of common and preferred stock repurchase programs. Although these statements are based upon Unocal's current expectations and beliefs, they are subject to known and unknown risks and uncertainties that could cause actual results and outcomes to differ materially from those described in, or implied by, the forward-looking statements, including market conditions for the company's securities; volatility in commodity prices; the extent of Unocal's operating cash flow and other capital resources available to fund its capital expenditures; and other factors discussed in Unocal's 2003 Annual Report on Form 10-K, as amended, and subsequent reports filed by Unocal with the Securities and Exchange Commission (SEC File No. 1-8483). Copies of the company's SEC filings are available from the company by calling 800-252-2233 or from the SEC by calling 800-SEC-0330. The reports are also available on the Unocal web site. Unocal undertakes no obligation to update the forward-looking statements in this news release to reflect future events or circumstances. All such statements are expressly qualified by this cautionary statement, which is provided pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934.

Updated: December 2004