The toluene insoluble portion of petroleum pitch A240 was oxidized using pure oxygen under high pressures in the range of 100-500 psi. The effects of oxidation temperature, pressure and time on the percentage of weight gain were investigated. Carbonization of the oxidized pitch samples indicated that the pitch samples were well stabilized after high pressure oxidation. Analyses of X-ray diffraction and Raman spectra showed that the pitch samples, after high pressure oxidation, changed from an easily graphitizable carbon material to non-graphitizable. Measurements of carbon yield showed a decrease with the increase of oxidation weight gain. (C) 2002 Elsevier Science B.V. All rights reserved.