The kinetics for direct synthesis of hydrogen peroxide out of hydrogen and oxygen has been studied over AuPd colloidal nanoparticles, which were prepared using a two-phase synthesis protocol. Reactions of direct formation of peroxide and peroxide reduction in the presence of hydrogen were studied separately to obtain the overall kinetic model, which was suitable to predict peroxide concentration at the outlet of the wall-coated microchannel reactor. The decomposition reaction was eliminated by the addition of sulfuric acid. The kinetic model of the direct formation of hydrogen peroxide from hydrogen and oxygen suggests hydrogen adsorption, pairwise dissociation, but not spill-over of H-species over the bimetallic AuPd surface. Peroxide concentration values predicted with an overall kinetic model and values experimentally measured at the outlet of the microchannel with a catalytic layer deposited on the wall are in acceptably good agreement.