Heteroepitaxial growth of CuCl films on CaF2(1 1 1) substrates has been studied by means of molecular beam epitaxy. Their morphology has been observed by atomic-force microscopy. Ultra thin films of CuCl are composed of nanocrystalline islands, the size of which depends critically on the substrate temperatures and growth rates. The coexistence of (1 1 1) A and B planes are identified by the arrangement of triangular holes. Their transmission, reflection and photoluminescence spectra have been measured around the energy region of excitonic resonance in order to get the average thickness and the optical properties of these films. (C) 2002 Elsevier Science B.V. All rights reserved.