dManganese(III)complexes of Salen, Br(2)Salen and (tert-butyl)(4)Salen ligands and their encapsulated analogues were prepared by the intrazeolite ligand synthesis (template synthesis) method. The oxidation of styrene was studied on the above catalysts using molecular oxygen as oxidant and tert-butyl hydroperoxide as initiator. The progress of the reactions was followed both by gas chromatography and by the oxygen consumed. The effect of the substituents on the encapsulation, on the catalytic activity and the effect of the encapsulation on the catalytic activity were studied and discussed.