Abstract Structural, optical and electrical properties of polycrystalline p‐type CuInSe 2 (CIS) thin films, grown by a process including a chemical reaction between Cu and In x Se y thin films deposited sequentially by evaporation, followed by annealing in a Se environment, were studied through XRD (X‐ray diffraction), transmittance and Hall voltage measurements. The conditions to grow CIS thin films in the α phase of the chalcopyrite structure were found through a parameter study. CIS films with these characteristics are usually used for the fabrication of high efficiency solar cells. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)