The orange yellow UO3 and bottle green U3O8 phases were prepared by thermal decomposition of uranyl nitrate hexahydrate at 400 degrees C and 500 degrees C, respectively. Gold catalysts supported on two oxides were prepared by incipient wetness impregnation for water-gas shift reaction. The gold catalysts were characterized by the techniques such as nitrogen physical adsorption, X-ray diffraction, temperature-programmed reduction, and X-ray photoelectron spectroscopy. The Au/UO3 catalyst has both microporous and mesoporous structures while the Au/U3O8 catalyst has only microporous structure. The presence of gold on the oxide surface greatly facilitates the reduction of uranium oxide support The active sites for water-gas shift reaction are likely dominant metallic gold with a small portion of oxidized gold species due to UO2+/U4+ redox property. The Au/UO3 catalyst shows higher activity with 55% conversion of CO in comparison with Au/U3O8. High activity on Au/UO3 catalyst is attributed to facile the reducibility of UO3 and its high surface gold atomic concentration. (C) 2015 Elsevier B.V. All rights reserved.