Abstract: A polycrystalline CuInSe.sub.2 film is produced by adding a liquid cooling medium to a mixture of Cu, In and Se powders, grinding the resulting composition by means of a ball-mill to provide a slurry containing CuInSe.sub.2 of low crystallinity, drying and adding a binding agent to the slurry to form a paste, coating a substrate with the paste, and sintering the paste so applied under a nitrogen atmosphere.The starting materials that can be used are not limited to respective powders of the above-mentioned elements but may be Cu-Se and In-Se compounds and the method provides CuInSe.sub.2 of excellent quality on a mass production scale at low cost.