The bromine （Br） and iodine （I） in raw coal, bottom ash （BA） and fly ash （FA） from seven thermal power plants （TPP） digested with pyrohydrolysis were determined by using inductively coupled plasma mass spectrometry （ICP-MS）. The distribution behavior of Br and I during coal combustion were researched and the environmental effects of Br and I in BA, FA and gas phase were analyzed. The results show that both elements Br and I in combustion products from TPP are usually pre- sent in decreasing order of the distribution rate as gas phase, FA and BA. In FA and BA, the distribution rate of Br （8.11% and 1.68%, respectively） are generally lower than that of I （9.26% and 4.67%, respectively）; on the contrary, in gas phase, the former （90.2%） is higher than the latter （86.9%）. In addition, for gas phase, the percentage of Br： （2.0%-75%） in total Br is generally larger than that of I2 （1.0%-10%） in total I. The environmental effects for Br and I emitted into atmosphere from TPP may be larger than those remained and captured by both FA and BA.
