<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2009-07-15</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001393718</issuerCik>
        <issuerName>SP Acquisition Holdings, Inc.</issuerName>
        <issuerTradingSymbol>DSP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001469099</rptOwnerCik>
            <rptOwnerName>STEEL PARTNERS II LIQUIDATING SERIES TRUST - F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001262861</rptOwnerCik>
            <rptOwnerName>STEEL PARTNERS II GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STEEL PARTNERS II, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000915653</rptOwnerCik>
            <rptOwnerName>STEEL PARTNERS II LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STEEL PARTNERS II, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001422282</rptOwnerCik>
            <rptOwnerName>Steel Partners LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STEEL PARTNERS II, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001452857</rptOwnerCik>
            <rptOwnerName>STEEL PARTNERS HOLDINGS L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STEEL PARTNERS II, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>590 MADISON AVENUE, 32ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $.001 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>668988</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 3 is filed jointly by Steel Partners II Liquidating Series Trust - Series F (&quot;Steel Partners Trust&quot;), Steel Partners II, L.P. (&quot;Steel Partners II&quot;), Steel Partners Holdings L.P. (&quot;Steel Holdings&quot;), Steel Partners LLC (&quot;Partners LLC&quot;) and Steel Partners II GP LLC (&quot;Steel Partners GP&quot;). Each of the Reporting Persons is a member of a &quot;group&quot; for purposes of Rule 13d-5(b)(1) of the Securities Exchange Act of 1934, as amended, with respect to the securities of the Issuer that beneficially owns in the aggregate in excess of 10% of the Issuer's outstanding shares of common stock. As members of the group, each of the Reporting Persons may be deemed to beneficially own the securities of the Issuer owned by the other members of the group.</footnote>
        <footnote id="F2">The shares reported in this Form 3 are beneficially owned directly by Steel Partners Trust, and owned indirectly by Steel Partners II by virtue of it being the record holder of the shares as nominee of Steel Partners Trust, by Steel Holdings by virtue of it being the sole limited partner of Steel Partners II, by Partners LLC by virtue of it being the manager of Steel Partners II and Steel Partners Trust and by Steel Partners GP by virtue of it being the general partner of Steel Partners II and the liquidating trustee of Steel Partners Trust. Steel Partners II, Steel Holdings, Partners LLC and Steel Partners GP disclaim beneficial ownership of the shares owned by Steel Partners Trust except to the extent of their pecuniary interest therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By: Steel Partners II Liquidating Series Trust - Series F, By: Steel Partners II GP LLC, as Liquidating Trustee, By: /s/ Sanford Antignas, as Attorney in Fact for Warren G. Lichtenstein, Managing Member</signatureName>
        <signatureDate>2009-07-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: Steel Partners II GP LLC, By: /s/ Sanford Antignas, as Attorney In Fact for Warren G. Lichtenstein, Managing Member</signatureName>
        <signatureDate>2009-07-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: Steel Partners II, L.P., By: Steel Partners II GP LLC, General Partner, By: /s/ Sanford Antignas, as Attorney in Fact for Warren G. Lichtenstein, Managing Member</signatureName>
        <signatureDate>2009-07-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: Steel Partners LLC, By: /s/ Sanford Antignas, as Attorney In Fact for Warren G. Lichtenstein, Manager</signatureName>
        <signatureDate>2009-07-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: Steel Partners Holdings L.P., By: Steel Partners II GP LLC, General Partner, By: /s/ Sanford Antignas, as Attorney In Fact for Warren G. Lichtenstein, Managing Member</signatureName>
        <signatureDate>2009-07-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
