In this study, monometallic Pt and bimetallic Pt-Ru, Pt-Ir were supported to γ-Al₂O₃. In order to distribute metals uniformly, H₂O-H₂ treatment method was used. Xylene and MEK were used as reactants. The monometallic or bimetallic catalysts were prepared by the excess wetness impregnation method and were characterized by XRD, XPS, TEM analysis. As a result, Pt-Ru, Pt-Ir bimetallic catalysts were showed higher conversion than Pt monometallic catalyst. The catalysts which used H₂O-H₂ treatment had better VOC`s conversion than that of nothing treatment on the γ-Al₂O₃ support. Pt-Ir bimetallic catalyst was showed highest conversion on the γ-Al₂O₃ support. The effect of H₂O-H₂ treatment was uniform distribution of Pt particles. The activation energy of H₂O-H₂ treatment catalysts were lower than that of nothing treatment ones on the γ-Al₂O₃ support. In this study, the use of small amount of Ru, Ir to Pt promoted oxidation conversion of VOCs. In addition to, H₂O-H₂ treatment promoted oxidation conversion of VOCs on the γ-Al₂O₃ support.