The apparent kinetics of H2S removal by ZnO in the presence of hydrogen were studied by thermogravimetric analysis. Experiments were carried out with spherical pellets of about phi 3 turn, at temperatures from 200 to 320 degreesC. For the purpose of comparison, experiments were also carried out in the absence of hydrogen. The results show that the kinetic behavior of the desulfurization could be described by the equivalent grain model. The activation energies of reaction and diffusion in H2S-N-2 and in H2S-N-2-H-2 systems were estimated and compared. The effect of hydrogen on desulfurization was also investigated.