Benzoic acid and benzaldehyde were obtained by gas-phase catalytic oxidation of toluene over V₂O₅ and heteropoly 12-molybdovanadophosphoric acid（H_3+nPMo_12-nV_nO₄₀）, The effects of reaction temperature, air/toluene mole ratio, and space velocity on the yields and selectivities were investigated. With H₄PMo₁₁V₁O₄₀ catalyst, the maximum selectivity of benzoic acid, 78 %, could be obtained at 450 ℃, with the space velocity of 1,585 l/hr/l-cat. and air/toluene mole ratio 272. The oxidizing power of catalysts in this work was as follows; V₂O₅>H₅PMo₁₀V₂O₄₀>H₆PMo₉V₃O₄₀>H₄PMo₁₁V₁O₄₀. For the catalytic oxidation mechanism, a redox reaction mechanism based upon the Langmuir-Hinshelwood approach was used.