Conventional removal of SO2 yields a large amount of waste salts or requires significant energy for regeneration of the absorbent. Phase-change capture has been considered a possible method to solve these problems since only the absorption product needs to be disposed for recovery and the solvent could be reused directly. In the present work, the phase-change absorption behavior of 1,3,5-trimethylpyrazole, 2-methylimidazole, 1-methylimidazole, and 1,2-dimethylimidazole has been investigated in organic solvent. Among these absorbents, only 1,2-dimethylimidazole exhibited an obvious phase-change performance in solvents three glycol dimethyl ether, propylene carbonate, and dimethylacetamide but not in butanol. The composition and structure of the absorption product were not related to the type of solvent but affected by the air. 1,2-Dimethylimidazole reacted with SO2 to form a charge-transfer complex, which converted to pyrosulfite (C5H9N2)(2)S2O5 in the presence of water. The absorption product was further oxidized to dithionate (C5H9N2)(2)S2O6 by oxygen from the air. Once the filtrate, which was created from the separation process of the phase-change product and solvent, was exposed to air for several days, another type of oxidative product (C5H9N2)(2)SO4 was discovered.