The influence of deposited Pt metal clusters on the CO photooxidation reaction on the TiO2(110) surface was investigated. An enhancement in the CO photooxidation reaction rate or yield is not observed in the presence of Pt metal clusters on the TiO2(110) surface. These results indicate that kinetic models involving Schottky-barrier electron trapping in metal deposits leading to enhanced electron-hole pair lifetimes are not applicable in the case of CO photooxidation on Pt/TiO2(110).