It has been demonstrated that radicals and/or anions can promote chain reactions improving desulfurization efficiency in flue gas. Recent studies have evidently shown that specially synthesized C12A7 is a prominent source of O- which has been found to be one of the most active radicals acting as a potential oxidant in many applications. In the interest of applying C12A7 in flue gas desulfurization for coal combustion facilities, reactions of C12A7 with SO2 at 200-700 degrees C were implemented in a plug flow reactor. Both SO2 removal efficiency and the apparent reaction rate constants derived from the experiments were compared with those of CaO. The products were analyzed by TG-MS and FTIR. The result showed that under the experimental conditions the reactivity of C12A7 directly reacted with SO2 Was lower than CaO samples because of its low surface area accessibility. The product analysis verified that O- in C12A7 was involved in desulfurization reaction as an effective oxidant. On the basis of these results, a feasible application approach for C12A7 in desulfurization process was suggested so as to improve SO2 removal efficiency. A preliminary experiment was further devised to support the feasibility.