Abstract The influence that various dopants exert on the behaviour of single crystalline SrTiO3 electrodes in a photoelectrochemical cell for water decomposition has been investigated. The electrodes were surface doped with Sr3MeNb2O9 (Me2+ = Mn, Fe, Co, Ni) and LaMeO3 (Me3+ = V, Cr, Mn, Fe, Co, Rh). The results have been compared with those for the sensitization of single crystalline SrTiO3 photoanodes homogeneously doped with LaCrO3 or the oxides of the transition metals Cr, Mn, Fe, Co, Ni, Nb, Mo, Ta and W. The response to visible light is greatest for Cr3+ and decreases in the sequence Co2+, Ni2+, Mn2+, Rh3+. The dopant ions V3+, Mn3+, Fe2+, Fe3+, Co3+ and the oxides of Nb, Mo, Ta and W reveal hardly any or no photosensitization. This is discussed in terms of a simple model proposed recently by members of our group.