This International Standard specifies an N-benzoyl-N-phenylhydroxylamine photometric method for the determination of the vanadium content of aluminium oxide primarily used for the production of aluminium. The method is applicable to products having a vanadium content, expressed as V2O5, between 0,000 3 and 0,016 % (m/m), provided that the Cr2O3 and the TiO2 contents do not exceed 0,002 and 0,006 % (m/m) respectively.