Reduction properties of nickel oxide, tungsten oxide, and nickel-tungsten oxide mixtures, supported on silica-alumina, were investigated by XRD analysis, oxygen titration and XPS spectra. The supported tungsten oxide contains various oxidation states of tungsten after being reduced at 600-degrees-C in an H-2 flow of atmospheric pressure. When cosupported with nickel oxide, part of the tungsten oxide was reduced to the metallic state. This suggested that reduction of tungsten is promoted in the presence of the more readily reduced nickel.