Exhibit
10.4

    


    AMENDED
AND RESTATED

    


    ENGAGEMENT
AGREEMENT

    


    Agreement
made and entered into as of June 11, 2010 between Hemispherx Biopharma, Inc. a
Delaware Corporation (the “Company”) and William A. Carter, M.D., of Tavernier,
Florida (“Carter”).

    


    In
consideration of the premises and the mutual covenants and conditions herein
contained the Company and Carter hereby agree as follows:

    


    1.           Engagement.  The
Company engages Carter and Carter agrees to serve the Company as a consultant
relating to patent development.  It is expressly understood and agreed that
all of Carter’s services hereunder are being provided as an independent
contractor and not as an employee for federal tax purposes.

    


    2.           Term.  This
Agreement shall commence as of June 1, 2010 and shall terminate on December 31,
2015 (the “Initial Termination Date”) unless sooner terminated in accordance
with Section 5 hereof or unless renewed as hereinafter provided (such period of
service together with any extension thereto hereinafter being called the
“Service Period”).  This Agreement shall be automatically renewed for
successive one (1) year periods after the original Termination Date unless
written notice of refusal to renew is given by one party to the other at least
ninety days prior to the initial Termination Date or the expiration of any
renewal period.

    


    3.           Fees. 

    


    (a)          For
his services to the Company the Company shall pay Carter a fee (the “Base Fee”)
of $300,000 per year (the “Original Base Fee”), which shall be subject to
adjustments as provided in succeeding subsections (b) and (c).

    


    (b)          On
January 1, 2011, and on January 1 of each succeeding calendar year during the
Service Period and after the adjustment provided for in subsection (b) above,
the Base Fee shall be increased by the greater of the percentage equal to the
percentage average increase or decrease in the Bureau of Labor Statistics
“Consumer Price Index – U.S. City Average – All Items” from the prior calendar
year or a universal, non-discriminatory Cost Of Living salary adjustment as
approved by the Compensation Committee.

    


    (c)           For
each calendar year (or part thereof) during which this Agreement is in effect,
Carter shall be eligible to be paid a performance bonus in an amount up to
twenty-five percent (25%) of his Base Fee then in effect, in the sole discretion
of the Compensation Committee of the Board of Directors based on Carter’s
performance for such year.     

    


    4.           Expenses. 
During the Service Period, Carter, upon presentation of payment vouchers or
receipts and as prescribed or limited by the Company’s Travel & Expense
policies and procedures, whenever practical given the demands of the business
requirements, will be reimbursed for the reasonable and necessary expenses
incurred by him in providing services pursuant to this
Agreement.


    
      
         


      

      
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    5.           Termination. 

    


    (a)           The
Company may discharge Carter for cause at any time as
provided herein.  For purposes hereof, “cause” shall mean the willful
engaging by Carter in illegal conduct, gross misconduct or gross violation of
the Company’s Code of Ethics And Business Conduct for Officers which is
demonstrably and materially injurious to the Company. for purposes of this
Agreement, no act, or failure to act, on Carter's part shall be deemed "willful"
unless done, or omitted to be done, by Carter not in good faith and without
reasonable belief that Carter's action or omission was in the best interest of
the Company.  Notwithstanding the foregoing, Carter shall not be deemed to
have been terminated for Cause unless and until the Company delivers to Carter a
copy of a resolution duly adopted by the affirmative vote of not less than
three-quarters of the entire membership of the Board at a meeting of the Board
called and held for such purpose (after reasonable notice to Carter and an
opportunity for Carter, together with counsel, to be heard before the Board)
finding that, in the good faith opinion of the Board, Carter was guilty of
conduct set forth above and specifying the particulars thereof in
detail.

     

    (b)           This
Agreement shall terminate upon the death or disability of Carter. 
For purposes of this subsection (b), “disability” shall mean the inability of
Carter effectively to substantially provide the services hereunder by reason of
any medically determinable physical or mental impairment which can be expected
to result in death or which has lasted or can be expected to last for a
continuous period of not less than twelve (12) months.

    


    
      (c)          Carter
shall have the right to terminate this Agreement upon not
less than thirty (30) days prior written notice of
termination.

    

    


    
      6.           Effect of
Termination.

    

    


    (a)           In
the event that this Agreement is terminated for "cause" pursuant to subsection
5(a),  the Company shall pay Carter, at the time of such termination, only
the fees due and payable to him through the date of the termination of this
Agreement.

    


    (b)           In
the event that this Agreement is terminated by the Company at any time without
"cause", as defined in subsection 5(a), the Company shall pay to Carter, at the
time of such termination, the fees otherwise due and payable to him through the
last day of the then current term of this Agreement.

    


    (c)           In
the event this Agreement is terminated at his election pursuant to subsection
5(c) or due to Carter’s death or disability pursuant to 5(b), the Company shall
pay to Carter, at the time of such termination, the fees otherwise due and
payable to him through the last day of the month in which such termination
occurs and for an additional twelve month period.

    


    7.           Carter’s Representations and
Warranties.  Carter hereby represents and warrants to the Company
that he has the right to enter into this Agreement, and his execution, delivery
and performance of this Agreement (a) will not violate any contract to which
Carter is a party or any applicable law or regulation nor give rise to any
rights in any other person or entity and (b) are not subject to the consent of
any other person or entity.

     

    
      
         

      

      
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    8.           Notices.  Any
notice or other communication pursuant to this Agreement shall be in writing and
shall be sent by telecopy or by certified or registered mail addressed to the
respective parties as follows:

    


    
      
        	  	
                (i) 

              	
                If
      to the Company, to:

              


      

    

     

    HEMISPHERX
BIOPHARMA, INC.

    One
Penn Center

    1617
JFK Boulevard

    Philadelphia,
Pennsylvania 19103

    Telecopier
No.: (215) 988-1739

    Attention:
Thomas Equels

    General
Counsel

    


    
      
        	  	
                (ii) 

              	
                If
      to Carter, to:

              


      

    

                         

    Dr.
William A. Carter, M.D.

    HEMISPHERX
BIOPHARMA, INC.

    One
Penn Center

    1617
JFK Boulevard

    Philadelphia,
Pennsylvania 19103

    Telecopier
No.: (215) 988-1739

    


    or
to such other address as the parties shall have designated by notice to the
other parties given in accordance with this section.  Any notice or other
communication shall be deemed to have been duly given if personally delivered or
mailed via registered or certified mail, postage prepaid, return receipt
requested, or, if sent by telecopy, when confirmed.

    


    9.           Modification. 
No modification or waiver of this Agreement or any provision hereof shall be
binding upon the party against whom enforcement of such modification or waiver
is sought unless it is made in writing and signed by or on behalf of both
parties hereto.

    


    10.         Miscellaneous. (a)
This Agreement shall be subject to and construed in accordance with the laws of
the State of Florida.

    


    (b)           The
waiver by either party of a breach of any provision of this Agreement by the
other party shall not operate and be construed as a waiver or a continuing
waiver by that party of the same or any subsequent breach of any provision of
this Agreement by the other party.

    


    (c)           If
any provisions of this Agreement or the application thereof to any person or
circumstance shall be determined by an arbitrator (or panel or arbitrators) or
any court of competent jurisdiction to be invalid or unenforceable to any
extent, the remainder hereof, or the application of such provision to persons or
circumstances other than those as to which it is so determined to be invalid or
unenforceable, shall not - be affected thereby, and each provision hereof shall
be valid and shall be enforced to the fullest extent permitted by
law.

     

    
      
         

      

      
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      (d)           This
Agreement shall be binding on and inure to the benefit of the parties hereto and
their respective heirs, executors and administrators, successors and
assigns.

    

    


    
      (e)           This
Agreement shall not be assignable in whole or in part by either party, except
that the Company may assign this Agreement to and it shall be binding upon any
subsidiary or affiliate of the Company or any person, firm or corporation with
which the Company may be merged or consolidated or which may acquire all or
substantially all of the assets of the Company.

    

    


    IN WITNESS WHEREOF, this
Agreement has been signed by the parties hereto as of the date first above
written.

    


    HEMISPHERX
BIOPHARMA, INC.

    


    
      
        	
                By:

              	
                /s/ Thomas K. Equels

              
	 
      	
                Thomas
      K. Equels, Secretary

              
	 
      	 
      
	
                By:

              	
                /s/ William A. Carter

              
	 
      	
                William
      A. Carter, M.D.

              


      

    

     

    
      
         


      

      
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