Several catalytic membranes have been studied, with different loadings and: radial distribution of the catalytic material. Two types of catalytic membranes have been prepared on top of alumina supports: (a) V/MgO membranes, where MgO was deposited in the support pores before impregnation with V, and (b) V/Al2O3 membranes, where the alumina supports were impregnated with a boehmite sol before V deposition. In both cases the introduction of V was carried only from the internal side of the porous tube, and using short impregnation times, in order to obtain a radial distribution of active material. The membranes prepared have been tested under reaction conditions, giving yields to propene of up to 15%. It was found that the best V/MgO membranes are more selective but less active than the best V/Al2O3 membranes. (C) 2000 Elsevier Science B.V. All rights reserved.