Abstract: A process is described for producing a composite metal film in which metalliferous particles and polymer particles are co-deposited on a substrate, the proportion of metalliferous particles being such that the metal film is discontinuous, the metal particles being present in the form of islands with intervening zones of polymeric material. The resulting composite films have negative temperature coefficient of resistance. The process may be applied to the production of semiconductor composite films, e.g., copper oxide films by means of an annealing oxidative treatment to convert metal to metal oxide before loss of polymeric matrix by oxidation or evaporation.