Abstract: The preparation of cementitious articles with a high surface finish, useful for the preparation of electrical devices, in particular photovoltaic devices, is described. The process involves exposing a prefabricated cementitious article to specific temperature and pressure intervals, for a given time period, and then coating the article thus treated with a polymer film, preferably based on polyimide, in specific quantities. Heat-resistant cementitious surfaces with a low, controlled and regular roughness, without pointlike defects, suitable for the deposition of additional thin films, in particular metallic films and absorbent films, typically used for the manufacture of photo voltaic cells and/or modules, are obtained.