VSi beta catalysts of V content varying between 0.14 and 4.0 V atoms/u.c., and containing VOx species of different coordination as shown by UV-vis spectroscopy, have been tested in oxidative dehydrogenation of propane. The catalytic performance depends on the V content, which controls the type of the VOx species. The catalyst of the lowest V content (0.14 V atoms/u.c.), in which isolated VO4 tetrahedra are observed, is active but not selective, the only reaction product being CO2. At higher V content up to 1.22 V atoms/u.c., propene appears in the reaction products, its selectivity increasing with the V content, i.e. with the increase in the amount of tetrahedral species up to 1.22 V atoms/u.c. At still higher V content, at which octahedral V species appear, the selectivity to propene decreases. C3H8 TPR measurements have shown that ODH of propane to propene may take place with the participation of the catalyst lattice oxygen, whereas this form of oxygen is not active in total combustion of the alkane. (c) 2006 Elsevier B.V. All rights reserved.