It was found from reduction experiment at 400 ℃ that kinetics of hydrogen adsorption over SiO2 or Al2O3 supported Pt catalyst were erhanced as acidity of supports were increased. H2 adsorption rate per unit area of Pt/Al2O3 was 15 time greater than that of Pt/SiO2. It is presumed that hydrogen spillover plays a role in this experiment.