Abstract: Nanosolid superacid SO₄^2-/TiO₂ was prepared by Sol-Gel method and soak method,and characterized by means of XRD,TEM,IR,XPS and specific surface area measurements.The results indicate that the SO₄^2-/TiO² grain sizes (≤ 30 nm) are smaller than pure TiO₂ and the specific surface area is greater than the pure TiO₂.In addition to the SO₄^2- are combined with metal ions(Ti⁴⁺) in a bidentate fashion.The binding energy of Ti⁴⁺ at SO₄^2-/TiO₂ is bigger than that of pure TiO₂.The acid strength was measured by the model reaction of the synthesis of ethyl acetate.The results also show that oxygen sensitivity as well as the working temperature are improved in comparison with the pure TiO₂.The relationship between the oxygen sensing properties and structure was discussed.