The preparation and modification of high effective Pd-Cu/C electrocatalysts toward ethanol oxidation reaction (EOR) in alkaline solution are investigated. A simple strategy through atmosphere-induced surface/structural modification is applied to promote their electrochemical performance. The alterations of EOR activities, structures and surface species of the prepared catalysts induced by H(2), O(2) or CO treatments are analyzed by CV, XRD and XPS techniques, respectively. It is observed that the degree of Pd-Cu alloying, surface Pd oxidation, CO oxidation and EOR activity are all promoted by the CO treatment at 470 K and the current density at -0.2 V of the as-prepared sample is enhanced about 190% due to the formation of perfect alloy core/PdO shell structure. (C) 2010 Elsevier B.V. All rights reserved.