The kinetics of H2S removal by zinc oxide desulfurizer was studied through thermogravimetric analysis. The experimental results show that desulfurization rate was controlled, at high temperature and low conversion, by the chemical reaction rate, and at low temperature and high conversion by the grain diffusion rate. The reaction is first order with respect to H2S concentration in the different controlled stages. The kinetic behavior can be modeled through the employment of the shrinking core model. The values of the model parameters were determined. The variation tendencies with temperature and concentration of H2S at the controlled stages were discussed.