In this work, the commercially available Jacobsen's catalyst, Mn(salen), was occluded in a hybrid polymeric membrane based on poly(dimethylsiloxane) (PDMS). This system was used as a catalytic barrier between two different phases: an organic substrate phase (cyclohexane, cyclooctene, cyclohexene or styrene) in the absence of solvent, and an aqueous solution of either t-BuOOH or H2O2. Such system was characterized by UV-vis spectroscopy, TGA, DTA, DSC, and SEM techniques. The occluded complex proved to be an efficient catalyst for the oxidation of alkanes and alkenes when t-BuOOH was used as oxidant. However, the hybrid polymeric membrane was a barrier against H2O2, preventing this oxidant from reaching the bulk of the membrane and oxidizing the substrate. (c) 2005 Elsevier B.V. All rights reserved.