Bimetallic Au-M (M = Ni, Cu, Ag, Pt, and Pd) catalysts supported on CeO(2) were prepared by step-by-step impregnation method for water-gas shift reaction. Among them Au-Pt/CeO(2) catalyst shows the highest activity with 78% conversion of CO at 250 degrees C. The action of platinum in Au-Pt/CeO(2) catalyst was investigated by means of X-ray diffraction, hydrogen temperature-programmed reduction, UV-vis diffuse reflection spectroscopy, and X-ray photoelectron spectroscopy. It is found that the introduction of platinum in Au-Pt/CeO(2) catalyst is responsible for the formation of partly oxidized gold species probably due to the interatomic charge transfer from Au 5d to Pt 5d band. The presence of both gold and platinum is beneficial to the reduction of ceria to Ce(3+) species as well as the creation of oxygen vacancies and makes the average size of ceria smaller. (C) 2010 Elsevier B.V. All rights reserved.