The catalyst Cu₃Pt₁–Cu₂O/SiC was facilely prepared via the in situ reaction of the corresponding compounds supported on SiC in the reaction stream. Cu₃Pt₁–Cu₂O/SiC exhibits excellent catalytic activity for the oxidation of alcohols (conversion of benzyl alcohol and selectivity of benzyl aldehyde are 93% and 98% respectively). The reduction of active Cu₂O to inactive Cu⁰ is the cause behind the deactivation of Cu/SiC. For Cu₃Pt₁–Cu₂O-7/SiC, a Cu₂O–Cu₃Pt₁ alloy formed under the reaction conditions plays an important role in the reaction. Active 5 nm Cu₂O nanoparticles are stabilized by the inactive Cu₃Pt₁ alloy, which was confirmed by control experiments, characterization results and a three-step experiment.