The effect of calcination temperature on the catalytic activity for water-gas-shift (WGS) reaction was investigated for copper/alumina catalysts prepared by the impregnation method. The catalyst calcined at 1073K, followed by the treatment in H 2 at 523K, showed a high activity for WGS reaction. XRD and H 2 -TPR measurements revealed that the catalyst calcined at 1073K contained both highly dispersed CuO and spinel CuAl 2 O 4 particles. The former species was reduced by the treatment in H 2 at 523K to yield the highly dispersed metallic copper which would act as catalytically active sites in WGS reaction.