A series of nanosized gold supported on CeO2, MnO2, and MnO2-CeO2 composite oxides have been prepared by a deposition-precipitation (DP) method and the effects of Mn/Ce atomic ratio on Au/MnO2-CeO2 catalysts and calcination temperature after loading gold for preferential oxidation of CO (PROX) in H2 stream have been investigated using a fixed-bed continuous-flow reactor at various temperatures. The catalysts were characterized by XRD, nitrogen sorption, TEM, and XPS. XRD analysis confirms the phase purity of CeO2 and MnO 2 phases and the fine dispersion of Au on Au/MnO2-CeO 2 catalysts. XPS analysis shows the formation of MnO 2-CeO2 solid phase with manganese loading on ceria support accompanied by an increase in Ce4+ surface concentration. ICP-AES demonstrates the increase in gold loading with manganese addition by DP method. A synergistic catalytic effect on conversion and selectivity was observed in the case of Au/MnO2-CeO2 catalysts, due to the coexistence of metallic and nonmetallic gold species within nano gold particle and the minor presence of Ce3+ species.