Exhibit 4.2


 


AMENDMENT
AGREEMENT


 


This
AMENDMENT AGREEMENT (the “Amendment”), dated as of December 28, 2017, is made by and between Ener-Core,
Inc., a Delaware corporation, with headquarters located at 8965 Research Drive, Suite 100, Irvine, California 92618 (the “Company”),
and the investor listed on the signature page attached hereto (the “Holder”). Capitalized terms used herein
and not otherwise defined herein shall have the respective meanings set forth in the November 2016 SPA (as defined below), as
applicable.


 


RECITALS


 


A.       Reference
is made to that certain Securities Purchase Agreement dated as of November 23, 2016, by and among the Company, the Holder and
the other investors listed on the signature pages attached thereto and party to a joinder agreement thereto (the “November
2016 SPA”), and the Senior Secured Notes issued to the Holder pursuant thereto (as amended from time to time prior to
the date hereof, the “November 2016 Notes”);


 


B.       The
Company and the Holder desire to amend the November 2016 SPA and each of the 2016 Notes as set forth herein; and


 


C.       In
compliance with Section 15 of the November 2016 Notes and the November 2016 SPA, this Amendment shall only be effective upon the
execution and delivery of this Amendment and agreements in form and substance identical to this Amendment (other than with respect
to the identity of the Holder and any provision regarding the reimbursement of legal fees) (together with this Amendment, the
“Amendments”) by other holders of the November 2016 Notes representing at least the Required Holders (as defined
in each of the November 2016 Notes) (such time, the “Effective Time”).


 


AGREEMENT


 


NOW
THEREFORE, in consideration of the foregoing mutual premises and the covenants and agreements hereinafter set forth, and for
other good and valuable consideration, the receipt, and legal adequacy of which is hereby acknowledged, the parties hereto, intending
to be legally bound, hereby agree as follows:


 


ARTICLE
I


SECURITIES
PURCHASE AGREEMENT


 


1.       Extension
of Listing Deadline. The first sentence of Section 4(f) of the November 2016 SPA is hereby amended and restated as follows:


 


“The
Company shall commence trading of its Common Stock on either The New York Stock Exchange, Inc., the NYSE American, The NASDAQ
Capital Market, The NASDAQ Global Select Market or The NASDAQ Global Market (collectively, the “Qualified Eligible Markets”)
no later than June 30, 2018 (the “Listing Deadline”).”


 






    	 	 	 



     


    

 


ARTICLE
II


NOTES


 


1.       Optional
Redemption at the Holder’s Election. The first sentence of Section 7 of the November 2016 Notes is hereby amended and
restated as follows:


 


“At
any time from and after July 1, 2018 and provided that the Company shall not have received either (i) initial deposits for at
least eight 2 megawatt (MW) Power Oxidizer units or (ii) firm purchase orders totaling not less than $3,500,000 and initial payment
collections of at least $1,600,000, in each case during the period commencing on the Issuance Date and ending on June 30, 2018
(inclusive), the Holder shall have the right, in its sole and absolute discretion, at any time or times, to require that the Company
redeem (a “Holder Optional Redemption”) all or any portion of the Conversion Amount of this Note then outstanding
by delivering written notice thereof (a “Holder Optional Redemption Notice” and the date the Holder delivers
such notice, the “Holder Optional Redemption Notice Date”) to the Company, which notice shall state (i) the
portion of this Note that is being redeemed and (ii) the date on which the Holder Optional Redemption shall occur, which date
shall be not less than three (3) Business Days from the Holder Optional Redemption Notice Date (the “Holder Optional
Redemption Date”).”


 


2.       Eligible
Market Deadline. Section 30(l) of the November 2016 Notes is hereby amended and restated as follows.


 


““Eligible
Market” means The New York Stock Exchange, The NASDAQ Global Market, The NASDAQ Global Select Market, The NASDAQ Capital
Market or the NYSE American or, on or prior to June 30, 2018, the Principal Market.”


 


ARTICLE
III


MISCELLANEOUS


 


1.       Effect
of this Amendment. This Amendment shall form a part of the November 2016 Notes for all purposes, and each holder of November
2016 Notes shall be bound hereby. This Amendment shall only be deemed to be in full force and effect from and after both the execution
of this Amendment by the parties hereto and the execution of Amendments substantially identical to this Amendment by the Company
and “Holders” holding at least a majority of the aggregate principal amount of the November 2016 Notes outstanding,
including the Lead Investor, as well as the Collateral Agent, that, together with undersigned, constitute the Required Holders.
From and after such effectiveness, any reference to the November 2016 Notes shall be deemed to be a reference to the November
2016 Notes, as amended hereby. Except as specifically amended as set forth herein, each term and condition of the November 2016
Notes shall continue in full force and effect.


 


2.       Entire
Agreement. This Amendment, together with the November 2016 SPA and November 2016 Notes, as amended to date, contains the entire
agreement of the parties with respect to the matters contemplated hereby and thereby, and supersedes any prior or contemporaneous
written or oral agreements between them concerning the subject matter of this Amendment.


 


3.       Governing
Law. This Amendment shall be governed by the internal law of the State of New York.


 


4.       Counterparts.
This Amendment may be executed in any number of counterparts and by different parties hereto in separate counterparts, each of
which when so executed and delivered shall be deemed an original, but all such counterparts together shall constitute but one
and the same instrument; signature pages may be detached from multiple separate counterparts and attached to a single counterpart
so that all signature pages are physically attached to the same document. This Amendment may be executed by fax or electronic
mail, in PDF format, and no party hereto may contest this Amendment’s validity solely because a signature was faxed or otherwise
sent electronically.


 


[Signature
Page Follows]


 






    	 	2	 



     


    







 


IN
WITNESS WHEREOF, the Holder and the Company have caused their respective signature pages to this Amendment to be duly executed
as of the date first written above.


 


	 	COMPANY:
	 	 
	 	ENER-CORE,
    INC.
	 	 
	 	 
	 	By:	 
	 	 	Name:
	 	 	Title: 


 


Signature
Page to Amendment Agreement—December 2017


 






    	 	 	 



     


    

 





IN
WITNESS WHEREOF, the Holder and the Company have caused their respective signature pages to this Amendment to be duly executed
as of the date first written above.


 





	 	HOLDER:
	 	 
	 	 
	 	By:	 
	 	 	Name:


 


Signature
Page to Amendment Agreement— December 2017