Abstract: Effect of hydrogen and oxygen on H2S removal by ZnO desulfurizer were investigated by thermogravimetric analysis. The microkinetics of desulfurization in the presence of hydrogen and oxygen were also studied. Experiments were carried out with spherical grain of 100mesh～120mesh, at temperatures from 200 ℃ to 320 ℃. The results show that hydrogen could accelerate the reaction in the range of 0%～40%. Oxygen had complicated influence on H2S removal because of the deposition of sulfur. The kinetic behaviors of desulfurization could be described by improved shrinking core model. The activation energies of reaction and diffusion were 14.96 kJ/mol and 46.77 kJ/mol, respectively.