ZnO nanoporous structures were prepared on indium-tin-oxide substrates by cathodic electrodeposition at low temperature without using any surfactant. The morphology and structure of the films were studied, and the mechanisms for the formation of the porous structures were also discussed. Dye-sensitized solar cells based on ZnO nanoporous films were fabricated. The cell performance was strongly dependent on ZnO film morphology. For porous ZnO coated with TiO2, cells with 1% power conversion efficiency were obtained. (C) 2008 The Electrochemical Society.