By anodic oxidation of copper sheets in sulfide anion-containing electrolytes copper chalcogenide semiconductor films suitable for photovoltaic applications can be attained. Anodically chalcopyrite (Cu2S) has been formed as pure, mechanically stable, homogeneous and adhesive polycrystalline films, consisting of well-developed large crystallites. Cu2S coated copper sheets were produced with an area of 3 cm x 3 cm. P-n-junctions formed by evaporation of CdS onto the anodically formed Cu2S films show an energy efficiency of 3.3%. The extension of this process to ternary systems, like copper/indium/sulfur, is likely to be possible. A mixture of Cu2S and CuInS2 could be formed by codepositing In2S3 together with Cu2S. Cu2Se-films with a thickness of up to 1 mu m were formed by chemical bath deposition.