The interaction energy of a single palladium or platinum atom on different alkaline-earth oxides has been determined by means of ab initio calculations on cluster models representing the nonpolar, nondefective (100) surface. The variation of the Madelung potential along the series implies a change on the polarization degree of the deposited metal atom but also an increase of the basicity of the oxide surface that allows a larger charge transfer at the interface. In addition, the presence of the oxide surface modifies the energetic position of the levels of the metal and depending on the metal, even the occupation of the metallic d-orbitals. As a consequence, a rather strong modification on the supported metal properties is found through the analysis of the adsorption of a CO molecule. (C) 2001 American Institute of Physics.