Anatase-type TiO2 films were formed on SiO2 film-coated glass substrates by a sol-gel method. Nanometer-sized gold particles were highly dispersed on the surfaces of the TiO2 film (Au/TiO2-TF) and TiO2 particles (Au/TiO2-P) using a deposition-precipitation method. X-ray photoelectron spectra of Au/TiO2-TF adsorbed with sulfur from S-8 molecules indicated that the sulfurs are selectively adsorbed on the Au surfaces with the two kinds of chemisorption modes, atomic and molecular adsorption (S-Au/TiO2-TF). Light-irradiation (lambda(ex) > 300 nm) to S-Au/TiO2-TF and S-Au/TiO2-P in water at 298 K gave rise to desorption of the sulfur with the Au particle size almost maintained. Kinetic analysis showed that the rate constant for the sulfur desorption from S-Au/TiO2-TF in an opened reaction system is larger than that from S-Au/TiO2-P in a closed reaction system by a factor of ca. 3.6. (c) 2006 The Electrochemical Society.