The oxidation of phenol and some chlorophenols by molecular oxygen at a concentration of similar to1.5x10(-4) mol dm(-3) has been studied in a small static titanium tubular reactor at temperatures of 648, 657, 673 K and pressures of 22 MPa. The effect of transition metal salts (CuSO4, VSO4, FeSO4, MnSO4, NiSO4, CoSO4), added in small environmentally acceptable amounts as homogeneous catalysts, was also studied, with copper showing a good catalytic effect.