A process compatible with large scale manufacturing was developed to prepare polycrystalline thin films of CuInSe2for photovoltaic applications. The technique involves the deposition of a multilayer (Cu‐In)nstack by magnetron sputtering onto Mo‐coated soda lime glass, followed by selenization by a method not requiring H2Se. The new selenization process involves the exposure of the annealed Cu‐In stack to Se while simultaneously ramping in temperature. The process results in high quality CuInSe2crystal growth with automatic convergence of valence stoichiometry. Properties of resulting films and heterojunction devices are described, with solar cell efficiencies of 8.9% so far having been attained.