To understand the sulfur recovery behavior during regeneration Of SO2-adsorbed sorbents in NH3, the reactions of SO2-NH3-H2O in the absence of O-2 are studied in a temperature range of 10-80 degrees C and feed NH3/SO2 molar ratios of 1-3. The solid products are analyzed by thermal gravimetric analysis, the element analysis, and the wet chemical analysis. The results show that the reactions are very fast and the products are mixtures of various types of ammonium-sulfites with (NH4)(2)SO3 as the main component. A lower temperature, a greater NH3/SO2 molar ratio, and a higher water vapor content favor the SO2 conversion to the sulfites. The amount of the sulfites collected and their composition are correlated to temperature and the feed NH3/SO2 molar ratios.