Superacid WO3/ZrO2 catalysts have been found to show a high activity and stability-in the reaction of gas-phase nitration of benzene with 70% HNO3. At 170degreesC and under atmospheric pressure the yield of nitrobenzene is within 65-80% at 99% selectivity for mononitrobenzene. The space time yield of nitrobenzene increases with increasing flow rate of reagents and amounts to 0.64 g/(g(cat) h).