UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 15

Certification and Notice of Termination of Registration Under Section 12(g) of
the Securities Exchange Act of 1934 or Suspension of Duty to File Reports
Under Sections 13 and 15(d) of the Securities Exchange Act of 1934.

Commission File Number 1-8483

Unocal Corporation

(Exact name of registrant as specified in its charter)

6001 Bollinger Canyon Road, San Ramon, California, 94583
(925) 842-1000

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

All securities listed on Exhibit A hereto.

(Title of each class of securities covered by this Form)

None

(Title of all other classes of securities for which a duty to file reports under section 13(a) or 15(d) remains)

     Please place an X in the box(es) to designate the appropriate rule provision(s) relied upon to terminate or suspend the duty to file reports:

Rule 12g-4(a)(1)(i)	o	Rule 12h-3(b)(1)(i)	þ
Rule 12g-4(a)(1)(ii)	o	Rule 12h-3(b)(1)(ii)	o
Rule 12g-4(a)(2)(i)	o	Rule 12h-3(b)(2)(i)	o
Rule 12g-4(a)(2)(ii)	o	Rule 12h-3(b)(2)(ii)	o
		Rule 15d-6	o

     Approximate number of holders of record as of the certification or notice date: Fewer than 300.

     Pursuant to the requirements of the Securities Exchange Act of 1934, Unocal Corporation has caused this certification/notice to be signed on its behalf by the undersigned duly authorized person.

DATE:   August 10, 2005	UNOCAL CORPORATION
	By:	/s/ KIMBERLEY C. SCHAFER
		Kimberley C. Schafer
		Assistant Corporate Secretary

Exhibit A

Security	Ticker
Common stock, par value $1.00 per share, of Unocal Corporation	UCL
Guarantee of 7.5% Debentures due 2029 of Union Oil Company of California	N/A
Guarantee of 7.350% Medium Term Notes due June 15, 2009 of Union Oil Company of California	N/A
Guarantee of 5.05% Senior Notes due 2012 of Union Oil Company of California	N/A
Guarantee of 6.5% Notes due 2008 of Union Oil Company of California	N/A
Guarantee of 7% Debentures due 2028 of Union Oil Company of California	N/A
Guarantee of 7.95% Series C Medium Term Notes due March 20, 2007 of Union Oil Company of California	N/A
Guarantee of 7.94% Series C Medium Term Notes due March 24, 2009 of Union Oil Company of California	N/A
Guarantee of 8.15% Series C Medium Term Notes due April 15, 2015 of Union Oil Company of California	N/A
Guarantee of 7.9% Series C Medium Term Notes due April 18, 2008 of Union Oil Company of California	N/A
Guarantee of 6.7% Series C Medium Term Notes due October 15, 2007 of Union Oil Company of California	N/A
Guarantee of 9.125% Debentures due February 15, 2006 of Union Oil Company of California	N/A
Guarantee of 9.18% Series B Medium Term Notes due February 15, 2006 of Union Oil Company of California	N/A
Guarantee of 9.4% Series B Medium Term Notes due February 15, 2011 of Union Oil Company of California	N/A
Guarantee of 9.375% Series B Medium Term Notes due February 15, 2011 of Union Oil Company of California	N/A
Guarantee of 9.34% Series B Medium Term Notes due February 15, 2011 of Union Oil Company of California	N/A
Guarantee of 9.15% Series B Medium Term Notes due February 15, 2006 of Union Oil Company of California	N/A
Guarantee of 9.35% Series B Medium Term Notes due March 4, 2011 of Union Oil Company of California
Guarantee of 6.25% Trust Convertible Preferred Securities	N/A
Guarantee of Trust Preferred Securities representing indirectly undivided beneficial interests in junior subordinated debentures of Unocal Corporation	N/A