PURPOSE: To prepare anthraquinone, in one step, economically in an industrial scale, by reacting toluene with oxygen in vapor phase in the presence of a catalyst containing Ag, Fe, Mo and/or phosphoric acid salt.

CONSTITUTION: Anthraquinone is prepared, economically, by the vapor-phase reaction of toluene with oxygen in the presence of a catalyst containing Ag, Fe, Mo and/or phosphoric acid salt, at 400W600°C. The catalyst containing Ag, Fe and/or Mo may contain other elements or compounds. The phosphoric acid salt is preferably a phosphate of one or more elements selected from theIb, IIb, IIIa, IVb, lanthanide, and VIII-groups of the periodic table. The catalyst may contain the compound in addition to Ag, Fe, Co or their compounds.