The anodic oxidation reactions of solid oxide fuel cells are studied by density functional theory method under different oxygen coverage on the Ni(1 1 1) surface. Co-adsorbed atoms can change the binding energy of adsorbed species, and then affect the reaction barriers. We analyze the detailed structures and atomic charges to explain the mechanism of oxygen coverage effect. Our results indicate that higher oxygen coverage (in the range between 0 and 219) leads to lower oxidation reaction barriers. The main reason of the effect is the charge transfer between species and Ni surface was changed by the electron acceptor of co-adsorbed oxygen atoms. (C) 2015 Elsevier B.V. All rights reserved.