SrTiO3 films were prepared on an indium-tin oxide (ITO)-coated glass plate by a spray-pyrolysis technique, and their photoelectrochemical anticorrosion effects for carbon steel substrates were examined. The photopotential of a SrTiO3 coating (ca. 1.5 mum thick) was -770 mV vs. Ag/AgCl in an aerated 3 wt % aqueous NaCl (pH 5) under illumination with 10 mW cm(-2) UV light. This potential was more negative than the corrosion potential of the bare steel (-500 mV). Corrosion of the carbon steel was substantially suppressed at pH 4 or higher pH in 3 wt % aqueous NaCl when it was connected to a SrTiO3-coated ITO under UV illumination.