The kinetics of n-butane oxidation to maleic anhydride over a commercial V-P-O catalyst for fluid bed reactors was investigated systematically and modelled according to a scheme of eight reactions, involving also the combustion of both n-butane and maleic anhydride to CO and CO2, as well as the formation and the combustion of acetic and acrylic acids. A, one-dimensional, heterogeneous (two-phase) fluid bed reactor model incorporating the independently derived kinetic scheme was successfully validated on a predictive basis against conversion, selectivity and steam production data collected in a full-scale MA production plant. (C) 2003 Elsevier Science Ltd. All rights reserved.