TPD, H-2-O-2 titration and TPR techniques have been used to study the effect of the surface oxygen species on hydrogen adsorption in an oxidized Pt/TiO2 catalyst system. Oxygen desorption peaks in the temperature range of 610-730 K were observed in the O-2-TPD profiles of the Pt/TiO2 samples oxidized in oxygen at temperatures 573, 673 and 773 K, respectively. They reveal that labile oxygen species were formed on the surfaces of these oxidized catalysts. Much more hydrogen spillover on the oxidized Pt/TiO2 catalysts was observed at room temperature using H-2-O-2 titration. The results from TPR and H-2-TPD experiments further support the proposal that the existence of labile oxygen species enhances hydrogen spillover in the system studied.