Hydrogarnet injected in two types of reactors in a pilot plant scale was found to be capable of reducing the amount of HCl from the effluent gas at high temperatures, for which conventional sorbents such as CaO and Ca(OH)(2) did not. HCl gas was fixed as chlorinate mayenite [Ca12Al10OSi4O32Cl6] at > 700degreesC under a realistic gas composition including H2O, CO2 and so on. Hydrogarnet also decreased the amount of hazardous by-products such as dioxins. (C) 2004 Elsevier B.V. All rights reserved.