A CATALYST USEFUL FOR THE OXIDATION OF ORGANIC COMPOUNDS, PARTICULARYL VAPOR-PHASE OXIDATION OF BENZENE WITH MOLECULAR OXYGEN TO PRODUCE MALEIC ANHDRIDE, COMPRISES THE OXIDES OF MOLYBDENUM, VANADIUM, PHOSPHORUS, SODIUM AND BOORON IN COMBINATION WITH AN OXIDE OF AT LEAST ONE METAL OF THE GROUP CONSISTING OF MANGANESE, TIN, TUNGSTEN AND BISMUTH, AND PREFERABLY ALSO IN COMBINATION WITH AN OXIDE OF AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF IRON, COBALT AND NICKEL.