The reaction mechanism of CO + NO on Pd/gamma-Al2O3 (110) has been studied using periodic density functional theory (DFT) calculations in detail. Three pathways to form CO2, N2O and N-2 were investigated by the kinetics and the electronic structure of catalyst. The calculated results indicate that the oxygen vacancy O-v plays an important role during the catalytic process, and Pd-O-v, pair embedded in gamma-Al2O3 is proposed to be an active site: The projected density of states (PDOS) analysis indicates that the formation of the oxygen vacancy O-v and the electron transfer between the surface Pd atom and CO or NO molecule are responsible for the catalytic activity of Pd/gamma-Al2O3 (110). (C) 2016 Elsevier B.V. All rights reserved.