Oxidative dehydrogenation of butane over a VMgO catalyst has been carried out in two fluidized bed steel reactors, with diameters of 6 and 10 cm, respectively. The use of a two-zone redox operating configuration (TZFBR) is shown to be advantageous compared to the conventional FBR mode for both reactors throughout the range of experimental conditions. The results obtained replicate those previously obtained on a small scale, and thus prove that the improvement previously observed in a small scale reactor were not due to spurious interactions between bubbles and the reactor wall. Yield and selectivity to the different reaction products are similar when the reactor scale is increased, whilst other variables establish the reactor performance. Under appropriate conditions, the TZFBR can be successfully employed in large reactors with the advantages of improved selectivity and safety. (C) 2004 Elsevier B.V. All rights reserved.