-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 KtaoPEIXXOQp5EZoLkYspn9wBgO8Jk8/bjlsDB+yLjh3DfDnojwJZke/AE69XFDt
 0iQ3IK7Aa+eEC/uRDPBZ5Q==

<SEC-DOCUMENT>0001295984-06-000048.txt : 20060516
<SEC-HEADER>0001295984-06-000048.hdr.sgml : 20060516
<ACCEPTANCE-DATETIME>20060516084010
ACCESSION NUMBER:		0001295984-06-000048
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060512
FILED AS OF DATE:		20060516
DATE AS OF CHANGE:		20060516

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GENCORP INC
		CENTRAL INDEX KEY:			0000040888
		STANDARD INDUSTRIAL CLASSIFICATION:	FABRICATED RUBBER PRODUCTS, NEC [3060]
		IRS NUMBER:				340244000
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1130

	BUSINESS ADDRESS:	
		STREET 1:		HIGHWAY 50 & AEROJET ROAD
		CITY:			RANCHO CORDOVA
		STATE:			CA
		ZIP:			95670
		BUSINESS PHONE:		9163554000

	MAIL ADDRESS:	
		STREET 1:		HIGHWAY 50 & AEROJET ROAD
		CITY:			RANCHO CORDOVA
		STATE:			CA
		ZIP:			95670

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GENERAL TIRE & RUBBER CO
		DATE OF NAME CHANGE:	19840330

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hudson Thomas R Jr
		CENTRAL INDEX KEY:			0001333606

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-01520
		FILM NUMBER:		06844085

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		203-854-1100

	MAIL ADDRESS:	
		STREET 1:		200 CONNECTICUT AVE
		STREET 2:		4TH FLOOR
		CITY:			NORWALK
		STATE:			CT
		ZIP:			06854

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Pirate Capital LLC
		CENTRAL INDEX KEY:			0001295984
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-01520
		FILM NUMBER:		06844086

	BUSINESS ADDRESS:	
		STREET 1:		200 CONNECTICUT AVENUE
		STREET 2:		4TH FLOOR
		CITY:			NORWALK
		STATE:			CT
		ZIP:			06854
		BUSINESS PHONE:		203 854 1100

	MAIL ADDRESS:	
		STREET 1:		200 CONNECTICUT AVENUE
		STREET 2:		4TH FLOOR
		CITY:			NORWALK
		STATE:			CT
		ZIP:			06854
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-05-12</periodOfReport>

    <issuer>
        <issuerCik>0000040888</issuerCik>
        <issuerName>GENCORP INC</issuerName>
        <issuerTradingSymbol>GY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001295984</rptOwnerCik>
            <rptOwnerName>Pirate Capital LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 CONNECTICUT AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06854</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See footnote 2</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001333606</rptOwnerCik>
            <rptOwnerName>Hudson Thomas R Jr</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 CONNECTICUT AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06854</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See footnote 2</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-05-12</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2006-05-12</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>X</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5083300</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote 1 and 2</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Put option (obligation to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>20.00</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-05-12</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2006-05-12</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>X</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-04-03</value>
            </exerciseDate>
            <expirationDate>
                <value>2006-05-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>290</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote 1 and 2</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The securities beneficially owned by the Reporting Persons are held directly by Jolly Roger Fund LP, a limited partnership for which Pirate Capital LLC (&quot;Pirate&quot;) serves as general partner, and Jolly Roger Offshore Fund LTD and Jolly Roger Activist Portfolio Company LTD, each an investment fund for which Pirate serves as investment advisor (collectively, the &quot;Funds&quot;). Pirate is deemed to be the indirect beneficial owner of the securities reported herein by reason of its position as general partner or investment advisor, as applicable, of the Funds, and its pecuniary interest in such shares is a fractional interest in such amount. Thomas R. Hudson Jr., as the sole managing member of Pirate, is also deemed to be the indirect beneficial owner of such securities. The Reporting Persons disclaim beneficial ownership of any and all such securities in excess of their actual pecuniary interest.</footnote>
        <footnote id="F2">David Lorber, who serves as a Director and Senior Investment Analyst of Pirate, is a member of the GenCorp Inc. board of directors.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Pirate Capital LLC, by Thomas R. Hudson Jr. its Portfolio Manager</signatureName>
        <signatureDate>2006-05-16</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Thomas R. Hudson Jr.</signatureName>
        <signatureDate>2006-05-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----