Photocatalytic activity in the visible part of the solar spectrum (442 nm) is demonstrated for highly organized mesoporous nanocrystalline titania thin films doped with thiourea. This property, which is of interest for the further development of photovoltaic devices operating in sunlight, is revealed by monitoring the photodegradation of methylene blue (see figure) upon contact with an N-doped TiO2 film as a function of irradiation time and film thickness.