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|Exhibit 24
POWER OF ATTORNEY
KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned, being a director or officer, or both, of MFRI, INC., a Delaware corporation (the Company), does hereby constitute and appoint DAVID UNGER,
HENRY M. MAUTNER and MICHAEL D. BENNETT, with full power to each of them to act alone, as the true
and lawful attorneys and agents of the undersigned, with full power of substitution and resubstitution
to each of said attorneys to execute, file or deliver any and all instruments and to do all acts
and things which said attorneys and agents, or any of them, deem advisable to enable the Company
to comply with the Securities Exchange Act of 1934, as amended, and any requirements or regulations
of the Securities and Exchange Commission in respect thereof, in connection with the Companys
filing of an annual report on Form 10-K for the Companys fiscal year 2005, including specifically,
but without limitation of the general authority hereby granted, the power and authority to sign his
name as a director or officer, or both, of the Company, as indicated below opposite his signature,
to the Form 10-K, and any amendment thereto; and each of the undersigned does hereby fully ratify
and confirm all that said attorneys and agents, or any of them, or the substitute of any of them,
shall do or cause to be done by virtue hereof.
IN WITNESS WHEREOF, each of the undersigned has executed this Power of Attorney as
of this 11th day of April, 2006.
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|/s/ David Unger                                                                                                |  | /s/ Arnold F. Brookstone      
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|David Unger, Chairman of the Board of Directors, and
    Chief Executive Officer (Principal Executive Officer) |  | Arnold F. Brookstone, Director
|                                                                                                               |  |                               
|/s/ Henry M. Mautner                                                                                           |  | /s/ Eugene Miller             
|                                                                                                               |  |                               
|Henry M. Mautner, Vice Chairman of the Board of 
    Directors                                                 |  | Eugene Miller, Director       
|                                                                                                               |  |                               
|/s/ Bradley E. Mautner                                                                                         |  | /s/ Stephen B. Schwartz       
|                                                                                                               |  |                               
|Bradley E. Mautner, Director and President                                                                     |  | Stephen B. Schwartz, Director 
|                                                                                                               |  |                               
|/s/ Michael D. Bennett                                                                                         |  | /s/ Dennis Kessler            
|                                                                                                               |  |                               
|Michael D. Bennett, Vice President, Secretary and 
    Treasurer (Principal Financial and Accounting Officer)  |  | Dennis Kessler, Director      
|                                                                                                               |  |                               
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