Physicochemical properties of bismuth vanadate catalysts with varying compositions, e.g., Bi4V6O21-6 1/2H2O·121NH3; Bi6V2O14·3 H2O; Bi6V4O19·6 H2O have been studied by chemical analysis, differential thermal analysis, thermogravimetry, infrared, X-ray diffraction, surface area and magnetic susceptibility techniques.