In this work effect of cobalt on catalyst CuO/CeO2 activity in selective CO oxidation in H-2-containing gases mixture was investigated. Catalysts were prepared by wet impregnation and calcination at 673 K, characterized by ICP, H-2-TPR, XRD, TEM, BET and XPS. The addition of cobalt to Cu/CeO2 catalyst improved the catalytic activity and selectivity for CO oxidation. Discussion of the results showed that the synergistic effect is correlated to better dispersion and reducibility of copper in the presence of the cobalt metal additive. More precisely, cobalt enhanced the segregation of copper phase towards the catalyst surface and copper enhanced CO oxidation at the expense of H-2 combustion.