Mesoporous CeO2-MnOx binary oxides with different Mn/Ce molar ratios were prepared by hydrothermal synthesis and characterized by scanning electron microscopy(SEM),N2 sorption,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS) and H2 temperature-programmed reduction(H2-TPR).The characterization results indicated that the CeO2-MnOx catalysts exhibited flower-like microspheres with high specific surface areas,and partial Mn cations could be incorporated into CeO2 lattice to form solid solution.The CeO2-MnOx catalysts showed better catalytic activity for CO oxidation than that prepared by the coprecipitation method.Furthermore,the CeO2-MnOx catalyst with Mn/Ce molar ratio of 1 in the synthesis gel(Ce-Mn-1) exhibited the best catalytic activity,over which the conversion of CO could achieve 90% at 135 oC.This was ascribed to presence of more Mn species with higher oxidation state on the surface and the better reducibility over the Ce-Mn-1 catalyst than other CeO2-MnOx catalysts. Mesoporous CeO2-MnOx binary oxides with different Mn / Ce molar ratios were prepared by hydrothermal synthesis and characterized by scanning electron microscopy (SEM), N2 sorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy The characterization results indicated that the CeO2-MnOx samples show flower-like microspheres with high specific surface areas, and partial Mn cations could be incorporated into CeO2 lattice to form solid solution. The CeO2-MnOx catalysts showed better catalytic activity for CO oxidation than that prepared by the coprecipitation method. Ferrthermore, the CeO2-MnOx catalyst with Mn / Ce molar ratio of 1 in the synthesis gel (Ce-Mn-1) exhibits the best catalytic activity, over which the conversion of CO could achieve 90% at 135 oC. This was ascribed to presence of more Mn species with higher oxidation state on the surface and the better reducibility over the Ce-Mn-1 catalyst than other CeO2-MnOx catalysts.