The mesoporous catalysts La-Co-Ce-O were successfully prepared in one step by citric acid complexation-organic template decomposition method, which show large surface area (up to 157 m(2)/g), narrow pore diameter distribution (3.7 similar to 3.9 nm), good thermal stability and high activity for CO and C3H8 oxidation. Based on the structural characterization results, it is found that the predominant Co phases are Co3O4 crystallites, and the activities of these mesoporous catalysts are not proportional to the amounts of surface cobalt atoms, but mainly related to the physical structure of the catalysts and the effective interaction between cobalt and cerium species. When the surface Co/Ce atomic ratio is close to 1, the catalytic synergy effect between them is maximized.