The complete reaction pathway for the selective alcohol oxidation to aldehyde has been obtained from periodic density functional theory (DFT) calculations on a series of catalyst models having Au atoms with different coordination number. A clear trend exists in the reactivity of the surfaces: it increases with decreasing the Au coordination number, suggesting that a distribution of Au sites with different activity might exist on the surface of real catalysts. This hypothesis emerging from the theoretical study has been experimentally confirmed by measuring the kinetics of benzyl alcohol oxidation on a series of Au/MgO catalysts having different particle diameter and therefore different concentration and distribution of low coordinated Au sites. (C) 2010 Elsevier Inc. All rights reserved.