The nanostructured composite catalytic membranes were prepared in situ in a membrane reactor by the molecular layering method (ML) of V-O and V-O-P catalytic structures deposition. The test operation of the membrane reactor was carried out for the oxidative dehydrogenation of methanol at two modes of reagents supply to a catalytic layer: at methanol diffusion through the membrane (MR-M) or at oxygen diffusion through the membrane (MR-O). The MR-M mode provided higher methanol conversion and selectivity by formaldehyde than the MR-O mode at introduction of methanol and oxygen by co-current flow. The V-O and V-O-P catalytic structures showed the different behavior depending on the mode of supply of methanol and oxygen to the catalytic layer. (C) 2007 Elsevier B.V. All rights reserved.