The use of an aerosol process to prepare vanadium phosphorus oxide (VPO) catalysts for butane oxidation to maleic anhydride was investigated. Heating an aerosol created with air of an aqueous solution of NH4VO3 and H3PO4 with phosphorus to vanadium atomic ratio P/V = 1.2 at 700 degrees C resulted ina material that had an average vanadium oxidation state of 4.7-5.0. After activation in a butane and oxygen mixture, a stable catalyst was obtained which showed selectivities to maleic anhydride (MA) of up to 48% at 475 degrees C. X-ray diffraction and laser Raman spectroscopic characterization of the catalyst showed that the as-prepared sample was mostly VOPO4 . 2H(2)O, which was converted to alpha(I)-VOPO4 under reaction conditions. The catalyst was much more active than a VPO catalyst with P/V = 1.1 or 1.2 prepared by the conventional method in an aqueous medium. Thus, in spite of its lower surface area and selectivity for MA, it produced a higher yield of MA even on the basis of the weight of catalyst.