The feasibility of n-butane partial oxidation to maleic anhydride (MA) over vanadium phosphorus oxide catalysts in an electrochemical membrane reactor in which an oxygen-ion-conducting electrolyte was used as the membrane was studied. Butane oxidation and oxygen separation were carried out simultaneously on the opposite surfaces of the membrane, and the oxygen flux transferred across the membrane was controlled by the external current between the two electrodes. At 751 K and with a current of 40 mA, the conversion of butane was 15-16%, and the selectivity to MA was about 39%. The selectivity and yield of MA increased with increasing applied current. The optimal reaction temperature was 750+/-5 K, as a compromise among the ionic conductivity of the membrane, the polarization resistances of the electrodes, and the selectivity and the yield of MA.