The photocurrent action spectra of S-doped anatase and rutile TiO2 films were measured in a solution of 0. 1 M HClO4 mixed with 0.5 mM of the reductants such as hydroquinone, KI, KSCN, and KBr at the applied voltage of +0.5 V. For the S-doped anatase TiO2 films, the incident photon to current efficiency (IPCE) was enhanced by the addition of hydroquinone or KI, while no enhancement was observed by the addition of other reductants. On the other hand, the IPCE for the S-doped rutile TiO2 films was enhanced for all of the reductants. It was suggested that the doped states were different between the S-doped anatase and rutile TiO2 films.