Mesoporous Mn-MCM-41 and Mo-MCM-41 molecular sieves were synthesized by hydrothernial method using manganese chloride, ammonium molybdate and sodium metasilicate as the source for Mn, Mo and Si.Mo(Im) Mn-MCM-41 was synthesized by impregnating Mn-MCM-41 with ammonium molybdate by wet chemical method. These materials were characterized by XRD, TGA, FT-IR and ESR techniques. The vapour phase oxidation of benzyl alcohol and cyclohexanol was attempted over these molecular sieves as a probe reaction. The principal products were benzaldehyde and cyclohexanone. The activity of Mn-MCM-41 was found to be better than the other two catalysts. The influence of time on stream was studied at 300degreesC for both the reactions over Mn-MCM-41 and Mo-MCM-41 molecular sieves. The conversion decreased very slightly with increase in time on stream.