Exhibit
10.1                                Facility
Letter Agreement Amendment

    


    
      May 1,
2009

    

    


    
      Fuel
Tech, Inc.

    

    27601
Bella Vista Parkway

    Warrenville,
IL  60555

    


    Attn: Mr.
John P. Graham, Chief Financial Officer & Sr. Vice President

    


    
      
        	
                Re: 

              	
                Loan
      Agreement dated as of July 31, 2006 (the “Agreement”) by and between Fuel
      Tech, Inc. (the “Borrower”) and Wachovia Bank, National Association (the
      “Bank”) in the original principal amount of $25,000,000, as amended from
      time to time.

              


      

    

    


    
      Obligor #
60-4198825142 - Obligation # 0000000034

    

    


    
      Dear Mr.
Graham:

    

    


    Borrower
and Bank hereby agree to amend the Loan Documents on the terms and conditions
set forth in this letter agreement.  The Agreement and all other
documents, including the Revolving Credit Note from Borrower to Bank, executed
and delivered in connection therewith are collectively referred to herein as the
“Loan Documents”.  All capitalized terms used but not defined herein
shall have the meanings assigned in the Loan Documents.

    


    Revolving Credit Commitment.
From the date of this letter agreement through the Revolving Credit
Termination Date, the Revolving Credit Amount is $15,000,000.

    


    Revolving Credit Termination
Date.  Borrower acknowledges that the Revolving Credit
Termination Date is July 31, 2009.

    


    Affirmations of Borrower.
Borrower affirms and represents that the Loan Documents, as modified hereby, and
other Loan Documents (as defined in the Loan Agreement)  are in full
force and effect, that Borrower has no defense to payment or performance of the
Obligations, that no setoffs against the Obligations exist, and that Borrower
has no counterclaims against Bank.  Borrower ratifies and confirms all
provisions of the Loan Documents.

    


    Miscellaneous. This letter
agreement and the other Loan Documents constitute the sole agreement of the
parties and supersede all oral negotiations and prior writings with respect to
the subject matter thereof.

    


    This
letter agreement may be executed in any number of counterparts and by the
different parties on separate counterparts and each such counterpart shall be
deemed to be an original, but all counterparts shall together constitute one and
the letter agreement.

    


    Please
indicate your agreement with the terms, affirmations and representations of this
letter agreement by signing it as provided below and returning it to the
undersigned within  five (5) days of the date hereof. Should you have
any questions, do not hesitate to call.

    


    Very
truly yours,

     

    
      
        
          
            
              
                
                  	 
      	
                          WACHOVIA BANK, NATIONAL ASSOCIATION

                        
	  	  
	  	  
	  	  	
                          By:

                        	      
                          /s/ Patrick J. Kaufman

                        	
                           

                        
	  	  	
                          Patrick J. Kaufmann

                        
	  	  	
                          Senior Vice President

                        


                

              

            

          

        

      

    

     

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    ACCEPTED AND AGREED TO:

    


    FUEL
TECH, INC.

    


     

      
        
          
            
              
                
                  	
                          By: 

                        	      
                          /s/ John P. Graham

                        	
                           

                        
	  	
                          John P. Graham

                        
	  	
                          Chief Financial Officer & Sr. Vice President