Know by all these presents, that the undersigned hereby constitutes
and appoints each of: Mark A. Whitney, Senior Vice President, General Counsel
and 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 a 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 Forms 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 GenCorp Inc. 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 GenCorp
Inc., 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 24th day of September 2008.


				/s/ Thomas A. Corcoran
				Thomas A. Corcoran