Carbon monoxide oxidation by nitrous oxide was carried out in a dielectric barrier discharge reactor operated under ambient conditions. It was observed that nonthermal plasma is effective in direct decomposition of N2O into nitrogen and atomic oxygen that promoted CO oxidation. Interesting observation is that plasma reactor has not shown significant activity for direct CO oxidation, whereas, presence of N2O improved the conversion of CO. Typical results indicated that the addition of ceria based catalysts improved CO conversion significantly, which was assigned due to adsorption/stabilization of atomic oxygen on the surface of the catalyst. Optimization of various parameters such as residence time of the gas, initial concentrations of CO, N2O and catalyst was done to achieve the best efficiency of the reactor. It was observed that conversion decreased with increasing flow rate of the gas and CO and N2O initial concentrations. Typical results indicated the best results at high residence of the gas time and low concentration of the reactants. Addition of catalyst improved the performance of the reactor due to synergetic effect between plasma excitation and catalytic action. Plasma reactor integrated with NiO/CeO 2 catalyst showed the best CO2 selectivity. © 2013 Elsevier B.V. All rights reserved.