Mesoporous MCM-41 molecular sieves substituted with various amounts of Cu(II) and Al(III) were synthesized by the hydrothermal method. The resultant materials were characterized by XRD, XANES. surface area and pore size measurement, EPR and Al-27 solid state NMR. The Cu(II)-substituted MCM-41 was found to be an efficient catalyst in the oxidation of trimethylphenol (TMP) to trimethylbenzoquinone (TMBQ) at mild reaction conditions. The latter is an intermediate in the manufacture of Vitamin E. The optimal activity was obtained when MCM-41 was concomitantly substituted with small amounts of Cu(II) and AI(III). The liquid phase reactions were extremely sensitive to the oxidant and solvent used. with acetonitrile as solvent, hydrogen peroxide and tert-butyl hydrogen peroxide were effective oxidants but with benzaldehyde as solvent, oxygen gas was also an effective oxidant.