The stability of metallic islands, epitaxially grown on a metallic substrate, is Studied by the evaluation of the island total energy. Hartree-Fock calculations at semiempirical level have been used to describe the island electronic configuration with quantum mechanical detail. The functional dependence of the island energy on the elements forming the island and the substrate (i.e. Ag, Cu and Fe). on the island geometry and on its state of stress, is analyzed and discussed. A similar analysis is also carried out for the barrier experienced by adatoms at descending steps. (C) 2002 Elsevier Science B.V. All rights reserved.