The adsorption of the reactants, O 2 and benzyl alcohol, on the cluster surface was performed in a step wise manner. Effectively all the atoms of the cluster are exposed to O 2 for adsorption and thereby all the 13 sites were investigated for adsorption in all 4 catalysts, with O 2 adsorbed over 4 Cu atoms in Cu 12 Au. The adsorption of O 2 on the catalyst is most stable in bridged manner in all 4 catalysts. The minimum energy complex of O 2 and catalyst was then considered for the adsorption of benzyl alcohol. Previous reports show that the benzyl alcohol adsorbs on the catalyst through cation-π and O-M interactions. The minimum energy complex of O 2 and catalyst was then used to study all possible benzyl alcohol adsorbed complexes to find the minimum energy adsorbate in all 4 catalysts. The minimum energy complex of catalyst, O 2 and benzyl alcohol was then adopted as the reactant molecule in the study of the reaction mechanism. The structures of these reactant molecules are shown in Co-adsorption energies of O 2 and benzyl alcohol show similar trend as for O 2 . The coadsorption energy was calculated to be -33.98, -39.42, -71.03 and -82.54 kcal/mol for Au 13 , Au 12 Cu, Cu 12 Au and Cu 13 respectively. Co-adsorption energies indicate that efficiency of the catalysts in oxidizing benzyl alcohol to benzaldehyde, making Cu 13 as the most efficient catalyst. While adsorption is a key process, desorption is also a significant step in catalysis. The Sabatier's principle explains the importance of interaction between reactants and catalyst, that it should not be too strong or too weak, as the former leads to products not leaving the catalyst surface while the latter leads to no reaction at all. The reaction rates observed experimentally can be understood through the desorption energies. The trends in desorption energies are discussed later.