Vanadium-magnesium mixed oxides have been prepared by thermal decomposition of decavanadate-intercalated Mg, Al layered double hydroxides (LDHs), MgAIVO-LDH, and by impregnation of MgO (mixed, MgAIVO-1, or not, MgVO-I, with Al2O3) With an aqueous decavanadate solution. The activity of catalyst MgAlVO-LDH in oxidative dehydrogenation of propane is higher than that measured for the mixed oxides obtained by conventional impregnation. However, the largest normalised conversion measured over sample MgAIVO-1 is assigned to the higher surface density of V centers, which are stabilised along the reaction runs. Normalised selectivity and conversion profiles show that propene is first formed and then oxidized to CO on catalyst MgAIVO-1, a process favoured by the high acidity of this solid. However, catalyst MgVO-I, with a medium strength surface acidity, is rapidly deactivated, forming CO2, by coke deposition on exposed V sites. The low selectivity to propene of catalyst MgAIVO-LDH is related to its low surface density of V sites. (c) 2008 Elsevier B.V. All rights reserved.