Perovskite-type Pr2-xSrxCoO4 +/-gimel mixed oxides were prepared by different calcination temperatures and were investigated by XRD, BET, TPD, TPR and XPS methods. These catalysts possess high catalytic activities towards the NO reduction by CO, and the activity of the PrSrCoO4 catalyst prepared by calcining at 750 degrees C is the best among these samples. This is explained in terms of its greater oxygen vacancies and larger BET surface areas. The influence of modification by a suitable amount of Pt-doping on the surface properties and catalytic activity for NO reduction by CO was studied. The results show that the Pt-modified PrSrCoO4 catalysts display activity significantly higher than that of the Pt-free system PrSrCoO4. Characterization of the catalysts by XRD, TPD, TPR and XPS methods reveals that both the surface and the bulk phase of the perovskite-type PrSrCoO4 play important roles in the catalytic activities for NO reduction by CO.