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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549

FORM 10-Q/A

For the quarterly period ended March 31, 2013

or

Commission file number: 000-52380

MISCOR GROUP, LTD.

(Exact name of registrant as specified in its charter)

800 Nave Road, SE

Massillon, OH 44646

(Address of principal executive offices/zip code)

Registrant’s telephone number, including area code: (330) 830-3500

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    x  Yes    ¨  No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    x  Yes    ¨  No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    ¨  Yes    x  No

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date. As of April 16, 2013, there were 11,684,987 shares outstanding of the issuer’s Common Stock, without par value.

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EXPLANATORY NOTE

This Form 10-Q/A is being filed in order to amend the original Form 10-Q for the period ending March 31, 2013, filed on May 13, 2013, to include as an exhibit the Agreement and Plan of Merger, dated as of March 13, 2013, by and among Integrated Electrical Services, Inc., MISCOR Group Ltd. (the “Company”), and IES Subsidiary Holdings, Inc. (the “Merger Agreement”). The Merger Agreement is incorporated by reference from MISCOR’s Form 8-K filed on March 13, 2013.

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MISCOR GROUP, LTD.

INDEX TO FORM 10-Q

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PART II - OTHER INFORMATION

The following documents are included or incorporated by reference in this Quarterly Report on Form 10-Q:

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

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EXHIBIT LIST