Catalytic oxidation over 0.5% Pt/γ-Al₂O₃ catalyst was carried out in supercritical fluid media. Deep conversion of BTX was increased as the reaction temperature was increased. The maximum conversion of benzene and toluene was 100% and 92.8% at 350℃ and 102 atm, respectively. Deep conversion was increased with pressure, it is explained by the molar density and the excellent diffusivity of the supercritical fluid media. From off-line sample, the many intermediates were detected by GC/MSD.