Perovskite-type oxide La0.6Ce0.4CoO3 and its doped Ag catalysts were prepared and their catalytic performances were evaluated for the direct decomposition of NO and the selective reduction of NO with propene in the presence of oxygen. A noticeable enhancement in activity was achieved by doping Ag and the optimum Ag loading was 1%. The effects of H2O, SO2, CO2 and O-2 on the performances of Ag/La0.6Ce0.4CoO3 catalysts for NO decomposition were also investigated. The resistance against H2O and SO2 appears satisfactory. The inhibition by CO2 is strong, although it is reversible. Oxygen did not inhibit the NO decomposition reaction but significantly promoted it. Compared with other perovskite-type oxides reported previously, higher conversions were obtained over the present catalysts for the NO reduction by propene. We speculate that the decomposition of NO is the predominant process even in the presence of propene. The catalysts were characterized by N-2-adsorption, XRD, XPS and NO-TPD and some explanations were put forward. (C) 2003 Elsevier Science B.V. All rights reserved.