-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 PQOt3uFSqZkBff+im61bRD0sA9VbVboInu5/PB0fwNfhV2qQKi/O0zyrSwNIuU3m
 BBu721SYBURPc470L0q2Aw==

<SEC-DOCUMENT>0001341074-08-000005.txt : 20080410
<SEC-HEADER>0001341074-08-000005.hdr.sgml : 20080410
<ACCEPTANCE-DATETIME>20080410160222
ACCESSION NUMBER:		0001341074-08-000005
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080408
FILED AS OF DATE:		20080410
DATE AS OF CHANGE:		20080410

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			IDEX CORP /DE/
		CENTRAL INDEX KEY:			0000832101
		STANDARD INDUSTRIAL CLASSIFICATION:	PUMPS & PUMPING EQUIPMENT [3561]
		IRS NUMBER:				363555336
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		630 DUNDEE RD STE 400
		CITY:			NORTHBROOK
		STATE:			IL
		ZIP:			60062
		BUSINESS PHONE:		8474987070

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NOTARO FRANK J
		CENTRAL INDEX KEY:			0001190862

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10235
		FILM NUMBER:		08750073

	BUSINESS ADDRESS:	
		STREET 1:		IDEX CORP
		STREET 2:		630 DUNDEE RD
		CITY:			NORTHBROOK
		STATE:			IL
		ZIP:			60062
		BUSINESS PHONE:		8474987070
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-04-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000832101</issuerCik>
        <issuerName>IDEX CORP /DE/</issuerName>
        <issuerTradingSymbol>IEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190862</rptOwnerCik>
            <rptOwnerName>NOTARO FRANK J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP-General Counsel &amp; Secretary</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2008-04-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4725</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15293</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>OPTIONS (RIGHT TO BUY)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>32.95</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-04-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>15760</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2009-04-08</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-04-08</value>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>15760</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>175003</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">MAY 7, 2007 FORM 4 REFLECTING 111,162 DERIVATIVE SECURITIES BENEFICIALLY OWNED OVERSTATED OWNERSHIP BY 5,000 SECURITIES DUE TO ERROR IN APRIL 6, 2006 FORM 4.</footnote>
        <footnote id="F2">ON MAY 21, 2007, THE COMPANY STOCK OF IDEX CORPORATION SPLIT 3 FOR 2, RESULTING IN THE REPORTING PERSON'S ACQUISITION OF 3,523 ADDITIONAL SHARES OF COMMON STOCK AND 53,081 ADDITIONAL OPTIONS.</footnote>
        <footnote id="F3">THE OPTION GRANT VESTS IN FOUR EQUAL INSTALLMENTS BEGINNING ON APRIL 8, 2009.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>FRANK J. NOTARO</signatureName>
        <signatureDate>2008-04-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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