A comparative study of the catalytic performance of a selective V-Mg-O catalyst in the oxidative dehydrogenation of n-butane is presented using three different types of reactor : (i) an adiabatic fixed-bed reactor; (ii) a fluidized-bed reactor; and (iii) an in situ redox fluidized-bed reactor. The results obtained indicate that the in situ redox fluidized-bed reactor outperforms the conventional fixed-and fluidized-bed reactors, especially at high n-butane conversions. Thus, a selectivity to C-4 olefins of 54% atn-butane conversions of 60% was achieved at 550 degrees C using an in situ redox fluidized-bed reactor while selectivities to C-4-olefins lower than 43% were obtained on the other reactor types under the same reaction conditions (isoconversion and reaction temperature).