Abstract: WO₃ nanomaterials were synthesized by hydrothermal method at different pH values，where the sodium tungstate was used as tungsten source and the mixture of potassium sulfate and oxalic acid was used as the complexing agents.The phase composition and microstructure were characterized.The results showed that the optimal WO₃ products had a single hexagonal crystal and were assembled by WO₃ nanorods.The morphology of the products changed from irregularity at pH value of 0.8，to microspheres at pH value of 1.0，finally to plate-like structure at pH value of 1.6.WO₃ microspheres showed the maximal effective surface area and uniform structure at pH value of 1.0.The synthesized WO₃ nanomaterials showed excellent gas sensing properties to NO₂.The highest response was obtained at an operating temperature of 100 ℃.WO₃ nanorods prepared with pH value of 1.0 at an operation temperature of 100 ℃ for different concentrations of NO₂ response-recovery characteristic curve analysis showed that，the response increased with the increase of the effective surface area of WO₃ nanomaterials and NO₂ concentration.The results demonstrate that it is an effective method to develop new-type mine gas sensors by microstructure design of the nanomaterials.

Key words: WO₃, Complexing agents, pH, NO₂, Gas sensing property