MCM-22 zeolite containing vanadium atoms either at structural or at ion-exchange positions was synthesized and tested in propane oxidative dehydrogenation (ODH) reaction in a fixed bed reactor, at temperatures between 340 and 560 degrees C. Acidity of these materials, as well as of similar materials that did not contain vanadium, was characterized by ammonia temperature programmed desorption (TPD-NH3). Vanadoaluminosilicates contain a higher number of acid sites, which present higher acidity in relation to the aluminosilicates. They also presented better performances in propane ODH, as they lead to higher values of conversion without loss of selectivity. Ion-exchange with alkaline ions leads to a decrease in cracking reactions, which are caused by strong Bronsted acid sites. (c) 2007 Elsevier B.V. All rights reserved.