Tungsten carbide (WC) is in the focus of current research as a suitable electrocatalyst support. Typically, supported monometallic system are investigated, in spite the fact that practice in catalysis shows that multimetallic systems can have significantly better performance compared to monometallic counterparts. In this work, WC-supported Pd3Au overlayers were studied theoretically using periodic Density Functional Theory calculations and compared to bulk-like Pd3Au and pure Pd. Stability of studied surfaces and the electronic structures were analyzed. Chemisorption properties were probed using atomic H and CO molecule. Electrocatalytic activities of studied surfaces were estimated using hydrogen binding energy as catalytic activity descriptor for hydrogen electrode reactions. The connection between H binding energy and CO adsorption energy enabled us to establish the link between catalytic activity and CO tolerance of studied surfaces. It is considered that formation of bimetallic layers on WC opens a new perspective in designing new core-shell electrocatalysts with high performance and significantly reduced content of noble metals. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.