This communication provides a detailed examination of the morphology of thin films of CuInSe2prepared by chemical spray pyrolysis on borosilicate glass, molybdenum‐coated glass, and CdS substrates. The latter two are used in thin‐film heterojunction solar cells of CuInSe2/CdS in the backwall and reverse backwall (RBW) configurations, respectively, and hence are of great technological interest. The pseudoepitaxial growth of CIS on CdS and its low deposition temperature (250 °C) which inhibits interdiffusion suggest that one should prepare CuInSe2/CdS solar cells in the RBW configuration.