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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 rKJg7sV891KG8u5LHmHeDg==

<SEC-DOCUMENT>0001209191-03-033784.txt : 20031205
<SEC-HEADER>0001209191-03-033784.hdr.sgml : 20031205
<ACCEPTANCE-DATETIME>20031205132934
ACCESSION NUMBER:		0001209191-03-033784
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031205
FILED AS OF DATE:		20031205

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:			JEFFRIES DOUGLAS
		CENTRAL INDEX KEY:			0001212520

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-01520
		FILM NUMBER:		031039832

	BUSINESS ADDRESS:	
		STREET 1:		C/O GENCORP INC.,
		STREET 2:		P.O. BOX 537012
		CITY:			SACRAMENTO
		STATE:			CA
		ZIP:			95853-7012
		BUSINESS PHONE:		9163518515

	MAIL ADDRESS:	
		STREET 1:		C/O GENCORP INC.,
		STREET 2:		P.O. BOX 537012
		CITY:			SACRAMENTO
		STATE:			CA
		ZIP:			95853-7012
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?><ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-12-05</periodOfReport><notSubjectToSection16>1</notSubjectToSection16>
    <issuer>
        <issuerCik>0000040888</issuerCik>
        <issuerName>GENCORP INC</issuerName>
        <issuerTradingSymbol>GY</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001212520</rptOwnerCik>
            <rptOwnerName>JEFFRIES DOUGLAS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>HIGHWAY 50 &amp; AEROJET ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>RANCHO CORDOVA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95670</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>VP, Controller</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-05</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>D</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>15000.0000</value></transactionShares><transactionPricePerShare><footnoteId id="F1" /></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts
><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2700.0000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Brokerage Account</value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-03</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F2" /></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShare
s><value>1830.9230</value></transactionShares><transactionPricePerShare><footnoteId id="F1" /></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2862.7510</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Plan Trust</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><footnotes><footnote id="F1">Due to the nature of this transaction, the Price of the Non-Derivative Security is not relevant to transaction. </footnote><footnote id="F2">Shares held in the GenCorp Retirement Savings Plan Trust ("Plan Trust") as of December 3, 2003 per the Plan Administrator's records.  The number of shares reported is calculated by dividing the dollar value of the participant's account by the closing stock price printed
 in the New York Stock Exchange Composite Transactions in the Wall Street Journal on the day reported above.  This calculation yields only the approximate number of shares in the participant's account because the cash component in the Plan Trust (target 2%) is allocated to each participant's account on a pro rata basis, and the cash component varies based on overall activity of all participants in the Plan Trust.

</footnote></footnotes><remarks></remarks><ownerSignature><signatureName>Mark A. Whitney as attorney-in-fact for Douglas Jeffries</signatureName><signatureDate>2003-12-05</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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