Ca(OH)(2)/fly ash sorbent has been studied as an effective method for SO2 removal. The effect of iron and other species for enhancing the ability of Ca(OH)(2)/fly ash sorbent was investigated in this study. At first, Fe(NO3)(3) was added in the preparation of the sorbent, and TG analysis was carried out. The Ca utilization rate over a period of 90 min was about 10% greater than that for Ca(OH)(2)/fly ash sorbent. However, it was found that iron is not effective for enhancing the ability of Ca(OH)(2)/fly ash sorbent but that NO3- was the most effective factor to enhance it. The mechanism of enhancing the Ca utilization rate was also investigated, and it was found that Ca(NO3)(2) was produced in the sorbent and reacted with SO2, so that the reaction Ca(NO3)(2) + SO2 -> CaSO4 + 2NO + O-2 proceeded.