POWER OF ATTORNEY


	Know by all these presents, that the undersigned
hereby constitutes and appoints each of: Mark A. Whitney, Vice President,
Law; Deputy General Counsel and Assistant Secretary; Rebecca A. Bauer,
Paralegal; and Yasmin R. Seyal, Senior Vice President and Chief Financial
Officer; and, signing singly, as the undersigned's true and lawful
attorney-in-fact to:

1.	execute for and on behalf of the undersigned,
in the undersigned's capacity as an executive officer and/or director of
GenCorp Inc., Forms 3, 4 and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder;

2.	do and
perform any and all acts for and on behalf of the undersigned which may be
necessary or desirable to complete and execute any such Form 3, 4 or 5,
complete and execute any amendment or amendments thereto, and timely file
such form with the United States Securities and Exchange Commission and any
stock exchange or similar authority; and

3.	take any other action of
any type whatsoever in connection with the foregoing which, in the opinion
of such attorney-in-fact, may be of benefit to, in the best interest of, or
legally required by, the undersigned, it being understood that the
documents executed by such attorney-in-fact on behalf of the undersigned
pursuant to this Power of Attorney shall be in such form and shall contain
such terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.

	The undersigned hereby grants to each
such attorney-in-fact full power and authority to do and perform any and
every act and thing whatsoever requisite, necessary, or proper to be done
in the exercise of any of the rights and powers herein granted, as fully to
all intents and purposes as the undersigned might or could do if personally
present, with full power of substitution or revocation, hereby ratifying
and confirming all that such attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause to be done by virtue
of this power of attorney and the rights and powers herein granted.  The
undersigned acknowledges that the foregoing attorneys-in-fact, in serving
in such capacity at the request of the undersigned, are not assuming, nor
is the Company assuming, any of the undersigned's responsibilities to
comply with Section 16 of the Securities Exchange Act of 1934.

	This
Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to
the undersigned's holdings of and transactions in securities issued by the
Company, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorneys-in-fact.

	IN WITNESS WHEREOF,
the undersigned has caused this Power of Attorney to be effective as of the
1st day of October, 2004.



						/s/ James M. Osterhoff

						James M. Osterhoff