Chloride volatilization characteristics of Cu, Pb, and Zn from MSW (Municipal Solid Waste) molten fly ash were studied using spent hydrochloric acid as a chlorinating agent. Experiments were carried out by using MSW molten fly ashes and model ashes to investigate the effect of Ca (Ca (OH)(2)) contained in the ashes on the chloride volatilization of heavy metals. When Ca-free model ash soaked with hydrochloric acid was heated at 1, 123 K, more than 96% of Cu, Pb, and Zn were volatilized. However, the volatilization of these metals decreased with an increase in Ca (OH)(2) content in the model ash. The volatilization behaviors of Cu, Pb and Zn in the model ash mixed with CaCl2 were almost the same as those in the model ash soaked with hydrochloric acid. It was considered that CaCl2 formed by the reaction of Ca (OH) and hydrochloric acid was responsible for the chloride volatilization of heavy metals. When the molten fly ash treated with a 20% excess molar concentration of hydrochloric acid over the Ca and heavy metals was heated at 1, 123 K, more than 99 % of Pb and Zn were volatilized, irrespective of the kind of molten fly ash. The volatilization of Cu was also increased from 10-20% to 35-60% by heating the molten fly ash to 1, 123 K, after soaking with hydrochloric acid. However, it was found that Cu was difficult to volatilize from the molten fly ash with a high Ca-content. SEM/EDS observation of the treated fly ash indicated that the surface of the fly ash was covered with CaCl2 melt in the heating process. It is considered that CaCl2 melt prevents the volatilization Of CuCl2, which has a low vapor pressure at this temperature.