Exhibit
        10.15

       

      ADDENDUM

      to

      PREFERRED
        STOCK PURCHASE AGREEMENT

      


      This
        ADDENDUM
        TO PREFERRED STOCK PURCHASE AGREEMENT (this
        “Addendum”), dated and effective as of June 1, 2005, is by and among Trulite,
        Inc., a Delaware corporation (the “Company”), Contango Contango Partners, L.P.,
        a Delaware limited partnership (“Investor”), J. Kevin Shurtleff and Andrew J.
        Nielson.

      


      W
        I T N E S S E T H:

      


      WHEREAS,
        the Company, Trulite Energy Partners, L.P., J. Kevin Shurtleff and Andrew
        J.
        Nielson entered into a Preferred Stock Purchase Agreement dated and effective
        as
        of July 26, 2004 (the “Purchase Agreement”); 

      


      WHEREAS,
        on February 2, 2005, Trulite Energy Partners, L.P. was merged with and into
        Investor;

      


      WHEREAS,
        pursuant to Section 11.5 of the Purchase Agreement, the Purchase Agreement
        may
        be amended
        with the consent of the Company, Investor and Messrs. Shurtleff and
        Nielson;

      


      WHEREAS,
        the Company, Investor and Messrs. Shurtleff and Nielson desire to enter into
        this Addendum pursuant to which Investor shall buy an additional 934,725
        shares
        of Series A Cumulative Convertible Preferred Stock, par value $0.0001 per
        share,
        of the Company (“Series A Preferred Stock”); and 

      


      WHEREAS,
        all capitalized terms not otherwise defined herein shall have the meaning
        ascribed to them in the Purchase Agreement.

      


      NOW,
        THEREFORE, the parties agree as follows:

      


      1.  Purchase
        of Series A Preferred Stock.
        

       

      (a) The
        Company has authorized the issuance and sale to Investor of 934,725 shares
        of
        Series A Preferred Stock, in exchange for aggregate cash consideration of
        $750,000.

       

      (b) On
        the
        date hereof, Investor shall purchase from the Company, and the Company shall
        issue and sell to Investor, 934,725 shares of Series A Preferred Stock in
        exchange for $750,000. 

      


      
        
           

        

        
           

          
            

          

        

        
           

        

      

      (c) On
        the
        date hereof, the Company shall deliver to Investor 934,725 shares of Series
        A
        Preferred Stock registered in the name of Investor, free and clear of any
        Lien,
        and Investor shall wire in same day funds $750,000 to such account as the
        Company may specify.

      


      2.  Acknowledgement.
        Each of
        the Company and Messrs. Shurtleff and Nielsen hereby acknowledge and agree
        that
        as of the effective date of the merger of Trulite Energy Partners, L.P. with
        and
        into Investor, Investor has been a party to the Purchase Agreement, Co-Sale
        Agreement, and Investor’s Rights Agreement as successor in interest thereto as a
        result of the merger with Trulite Energy Partners, L.P., and has enjoyed,
        and
        shall continue to enjoy, all the rights and benefits of Trulite Energy Partners,
        L.P. granted thereunder.

      


      3.  Representations
        and Warranties.
        Except
        as otherwise disclosed in writing to the Company or Investor, as the case
        may
        be, all of the representations and warranties of the Company and the Principal
        Stockholders and the Investors under the Purchase Agreement are true and
        correct
        as of the date hereof as if made on the date hereof.

      


      4.  Applicable
        Law.
        This
        Amendment shall be governed by, and shall be construed and enforced in
        accordance with, the substantive laws of the State of Texas.

      


      5.  Extent
        of Amendments and References.
        Except
        as otherwise expressly provided herein, the Purchase Agreement and the other
        agreements referred to therein are not amended, modified or affected by this
        Amendment. Except as expressly set forth herein, all of the terms, conditions,
        covenants, representations, warranties and all other provisions of the Purchase
        Agreement are herein ratified and confirmed and shall remain in full force
        and
        effect. From and after the effectiveness of this Addendum, the terms “this
        Agreement”, “hereof”, “herein”, “hereunder” and terms of like import, when used
        herein or in the Purchase Agreement shall, except where the context otherwise
        requires, refer to the Purchase Agreement, as amended by this
        Addendum.

      


      6.  Entire
        Agreement.
        This
        Addendum contains the entire agreement of the parties concerning the subject
        matter hereof. In the event of irreconcilable conflict between this Addendum
        and
        the other documents contemplated hereby, the provisions of this Addendum
        shall
        control.

      


      7.   Counterparts.
        This
        Amendment may be executed in one or more counterparts, each of which shall
        be
        deemed to be an original, but all of which shall constitute one and the same
        Addendum.

      


      [Signatures
        are on following page.]

      


      
        
           

        

        
           

          
            

          

        

        
           

        

      

      IN
        WITNESS WHEREOF, the parties hereto have caused this Agreement to be signed
        themselves or by its duly authorized officers as of the date first written
        above.

      
        	 	 	 
	 	TRULITE,
                INC.
	 	 
	 	
	 	 
	 	By:  	/s/ 
                John Sifonis
	 	
                
John
                Sifonis
	 	President
                and Chief Executive Officer


        	 	 	 
	 	 
	 	CONTANGO
                CAPITAL PARTNERS, L.P.
	 
 	 
 	 
 
	 	By:  	Contango
                Capital Partnership Management, LLC, its general partner
	 	
              
	 	
                

              
	 	
                
William
                J. Berger
	 	President and Chief Executive Officer