A 1% bismuth-doped VPO catalyst was prepared by refluxing Bi(NO3)(3) and VOPO4 . 2H(2)O in isobutanol. The incorporation of Bi into the VPO lattice lowered the overall V oxidation state from 4.24 to 4.08. It also lowered both the peak maximum temperature for the desorption of oxygen from the lattice from 1001 K (undoped) to 964 K with a shoulder at 912 K and the peak maxima for H-2 temperature-programed reduction from 863, 1011 and 1143 K ( undoped) to 798, 906 and 1151 K. The total oxygen desorbed from the Bi-doped catalyst was only one-fourth that of the undoped catalyst, while the amount of oxygen removed by TPR was roughly the same for both catalysts. These results suggest that in anaerobic oxidation, the Bi-doped catalyst will have roughly the same activity as in undoped catalyst in C-4 hydrocarbon oxidation but will have a higher selectivity to products such as olefins and maleic anhydride.