Adsorption of small metal particles Pd-3 and Pt-3 on an Al-terminated surface alpha-Al2O3(0 0 0 1) was studied by means of all-electron scalar relativistic density functional calculations. We employed stoichiometric model clusters and our recently developed embedding scheme which accurately accounts for the adsorption-induced substrate relaxation. We compared M-3 particles oriented parallel to and almost upright on the surface. The calculations show upright species which interact with two 0 anions and are stabilized by nearby Al cations to be most stable, with adsorption energies of 1.5 eV (Pd-3) and 2.6 eV (Pt-3). We also discuss the important role of substrate rearrangement. (C) 2003 Published by Elsevier Science B.V.