UV light irradiation of TiO2 (lambda > 320 nm) in a mixed solution of AgNO3 and S-8 has led to the formation of Ag2S quantum dots (QDs) on TiO2, while Ag nanoparticles (NPs) are photodeposited without S-8. Photoelectrochemical measurements indicated that the Ag2S photodeposition proceeds via the preferential reduction of Ag+ ions to Ag-0, followed by the chemical reaction with S-8. The application of this in situ photodeposition technique to mesoporous (mp) TiO2 nanocrystalline films coated on fluorine-doped SnO2 (FTO) electrodes enables formation of Ag2S QDs (Ag2S/mp-TiO2/FTO). Ag2S/mp-TiO2/FTO has the interband transition absorption in the whole visible region, While in the spectrum of Ag/mp-TiO2/FTO, a localized surface plasmon resonance absorption of Ag NPs is present centered at 490 nm. Ag2S QD-sensitized photoelectrochemical cells using the Ag2S/mp-TiO2/FTO and Ag/mp-TiO2/FTO photoanodes were fabricated. Under illumination of one sun, the Ag2S photoanode cell yielded H-2 at a rate of 0.8 mL . h(-1) with a total conversion efficiency of 0.29%, whereas the Ag/mp-TiO2/FTO photoanode is inactive.