The influence of a metal oxide support on the reactivity of adsorbed metals is a key question in surface reactivity and heterogeneous catalysis. Density functional theory (DFT) calculations are used here to examine support effects on one diagnostic of reactivity, oxygen binding, for Pd, Pt, Ag, and Au atoms supported on two representations of an alpha-alumina surface. Supported metal atoms uniformly bind oxygen more strongly than unsupported ones, so that even supported Au exothermically binds O. Further, oxygen adsorption is enhanced on a hydroxylated support by spillover of H from support to M-O bond. (C) 2009 Elsevier B. V. All rights reserved.