CuOx/SiO(2)precursor　was　successfully　fabricated　by　an　ammonia　evaporation　hydrothermal　method.　Upon　reduction　in　5　vol　%　H-2/N(2)at　250,　300,　350,　400,　or　450　degrees　C,　CuO　and　copper　phyllosilicate　species　in　the　precursor　bring　about　the　formation　of　highly　dispersed　Cu(0)and　Cu(+)species,　respectively.　The　Cu+/Cu(0)ratios　were　studied　by　XAES　technique,　while　the　particle　sizes　were　estimated　on　the　basis　of　HRTEM　images.　It　is　disclosed　that　the　ratios　and　particle　sizes　varied　with　CuOx/SiO(2)reduction　temperatures.　The　results　ofin　situDRIFTS　and　XAES　characterization　reveal　that　both　Cu(0)and　Cu(+)are　active　for　CO　adsorption　and　water　dissociation,　especially　so　with　Cu(0)and　Cu(+)particles　of　small　sizes.　It　was　also　observed　that　the　adsorption　of　CO　on　Cu(+)is　stronger　than　that　on　Cu-0,　and　Cu(0)is　more　active　than　Cu(+)for　water　dissociation.　Among　the　prepared　Cu/SiO(2)catalysts,　the　one　resulted　from　precursor　reduction　at　300　degrees　C　shows　the　highest　CO　conversion　in　WGS　reaction,　which　is　attributed　to　the　small　size　of　Cu-0(2.45　nm)　and　the　large　amount　of　Cu+.