-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001181431-08-032365.txt : 20080516
<SEC-HEADER>0001181431-08-032365.hdr.sgml : 20080516
<ACCEPTANCE-DATETIME>20080516210939
ACCESSION NUMBER:		0001181431-08-032365
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080515
FILED AS OF DATE:		20080516
DATE AS OF CHANGE:		20080516

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RENTECH INC /CO/
		CENTRAL INDEX KEY:			0000868725
		STANDARD INDUSTRIAL CLASSIFICATION:	PAINTS, VARNISHES, LACQUERS, ENAMELS & ALLIED PRODUCTS [2851]
		IRS NUMBER:				840957421
		STATE OF INCORPORATION:			CO
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		10877 WILSHIRE BLVD, #710
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90024
		BUSINESS PHONE:		310-571-9800

	MAIL ADDRESS:	
		STREET 1:		10877 WILSHIRE BLVD, #710
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90024

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kerr I Merrick
		CENTRAL INDEX KEY:			0001362912

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15795
		FILM NUMBER:		08843803

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		310.208.7160

	MAIL ADDRESS:	
		STREET 1:		10877 WILSHIRE BLVD SUITE 710
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90024
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd207250.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000868725</issuerCik>
        <issuerName>RENTECH INC /CO/</issuerName>
        <issuerTradingSymbol>RTK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001362912</rptOwnerCik>
            <rptOwnerName>Kerr I Merrick</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10877 WILSHIRE BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 710</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90024</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO &amp; Executive Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-05-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>39366</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.39</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>254813</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Purchase</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.15</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-07-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>75000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>75000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents 39,366 shares of common stock withheld by the Company for the payment of the employee's withholding taxes due upon the vesting and settlement of 108,333 shares of common stock pursuant to a restricted stock unit on May 15, 2008.</footnote>
        <footnote id="F2">Includes 108,334 shares of common stock issuable upon the vesting and settlement of a restricted stock unit.  The restricted stock unit vests and may be settled in 108,334 shares of common stock on May 15, 2009, subject to the reporting person's continued employment with the Company on each such date.</footnote>
        <footnote id="F3">The option vests in three equal installments of common stock on the first, second and third anniversaries of the grant date (July 14, 2006), subject to reporting person's continued employment with the company on each such date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/  I. Merrick Kerr</signatureName>
        <signatureDate>2008-05-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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