Abstract: A method for production of phenol or nucleus-substituted phenols from benzoic acid or nucleus-substituted benzoic acids by gas-phase catalytic oxidation characterized by using an oxide catalyst of the formula,Mo.sub.a W.sub.b X.sub.c Y.sub.d Z.sub.e O.sub.fwherein Mo is molybdenum, W is at least one of vanadium, niobium and tantalum, X is at least one of copper, silver, manganese, iron, cobalt, nickel, rhodium, palladium and platinum, Y is at least one of cerium, uranium, zirconium, chromium, tungsten, zinc, cadmium, tin, phosphorus, antimony, bismuth and tellurium, Z is at least one of thallium, alkali metals and alkaline earth metals, and when a is fixed to 12, b is 0.1 to 60, c is 0.1 to 60, d is 0 to 24, e is 0.1 to 120 and f is the number of oxygen atoms satisfying the valence of other elements.