Placement Agent Agreement

Exhibit 1.2

April 28, 2009

The Benchmark Company LLC

40 Fulton Street

19th Floor

New York, NY 10038

Ladies and Gentlemen:

Reference is made to (i) that certain Placement Agent Agreement (the “First Placement Agent Agreement”), dated April 2, 2009, between Emerging Growth Equities, Ltd. (“EGE”), as placement agent and CombiMatrix Corporation (the “Company”), (ii) that certain Placement Agent Agreement (the “Second Placement Agent Agreement”) between EGE as Placement Agent and the Company, dated April 28, 2009, with respect to the issuance and sale (the “Offering”) of  up to an aggregate of 1,100,000 shares of the Company’s common stock, $0.001 par value (the “Common Stock”) and warrants to purchase up to 1,100,000 shares of Common Stock (the “Warrants”, and together with the Common Stock, the “Securities”), and (iii) that certain Selected Dealer Agreement (the “Selected Dealer Agreement”), dated April 13, 2009, between EGE as placement agent and