To develop an easily regenerable zinc oxide high-temperature desulfurization sorbent, the role of H2O in the course of oxidative regeneration of zinc sulfide in the presence of O-2 were studied using ZnO without support material as a sorbent. Oxidative regeneration of ZnS in the presence of water vapor was examined using TPR technique and (H2O)-O-18, From this study, the following results were obtained: ZnS was converted to SO2 and H-2 by H2O in the absence of O-2 at high temperature (> ca. 600 degrees C); in the first step in the oxidative regeneration, ZnS predominantly reacted with H2O more than O-2; the SO2 formed from ZnS contained oxygen from H2O. From the experimental results, it was found that the oxidative regeneration of ZnS in the presence of H2O and O-2 can be expressed by the following two equations: ZnS + 3H(2)O <-> ZnO + SO2 + 3H(2); 3H(2) + 3/2O(2) --> 3H(2)O. In the absence of H2O or in the case of very low value of H2O/O-2 concentration ratio, the following reaction also occurred: ZnS + 3/2O(2) --> ZnO + SO2.