Vanadium and/or molybdenum oxides supported on mesoporous alumina have been prepared by a "wet" impregnation method, characterized (by using several physico-chemical techniques TPR, DR-UV-vis, Raman spectroscopies) and tested in the oxidative dehydrogenation (ODH) of ethane. For comparison Mo-V-mixed oxides supported on gamma-Al2O3 have also been studied. The characterization results indicate that the main vanadium species in both Mo-free and Mo-containing V-based samples present low aggregation and coordination, whereas molybdenum is present as monomeric or polymeric tetrahedral molybdenum species. Interestingly, no apparent interaction between molybdenum and vanadia takes place. The catalytic results show that V-containing catalysts are ca. four times more active than pure Mo-catalyst, whereas Mo-V-containing catalysts resulted to be the most selective ones in the ODH of ethane to ethylene, indicating that a synergetic effect between Mo and V takes place. In all cases, catalysts supported on mesoporous alumina were more active and selective in the ODH of ethane than the corresponding catalysts supported on gamma-Al2O3. (C) 2006 Elsevier B.V. All rights reserved.