Abstract: A non-noble metal catalyst was prepared by loading cobalt and nickel on activated carbon through saturated impregnation; it was characterized by XRD, SEM and TPD and used in preferential oxidation of CO in H₂-rich stream. The influence of water vapor and/or CO₂ on the performance of this non-noble metal catalyst was also examined. The results indicted that NiO and finely dispersed Co₃O₄ are formed in the catalyst; the catalyst exhibits stronger adsorption ability to O₂ than to CO₂ and the adsorption ability to O₂ increases with the loading of metal oxides. The non-noble metal catalyst exhibits high activity and selectivity in the preferential oxidation of CO. Over the catalyst CN250(35) with a metal oxide loading of 35%, CO concentration can be decreased to 40×10^-6 at 433K~473K; meanwhile, the selectivity of O₂ consumed by CO oxidation exceeds 50% at 473K. Moreover, the non-noble metal catalyst exhibits good resistance to water vapor and CO₂ in the stream. These suggest that current catalyst may meet the requests in purification of H₂ feed for PEMFC fuel cell application.