In this work, adsorption of vapour-phase elemental mercury (Hg-0) from pulverised-coal combustion flue gas by commercially available granular activated carbons treated with zinc chloride (ZnCl2) impregnation was investigated. The experiment results showed that ZnCl2 impregnation significantly enhanced the adsorptive capacity for mercury vapour, but decreased the specific surface area of the activated carbon. This could be explained by the occurrence of chemisorption, which was confirmed by adsorption tests over a wide range of temperatures. The influence of ZnCl2 solution concentration on the mercury removal performance was also studied. Mechanisms of mercury adsorption onto the Cl-impregnated activated carbon were proposed. (C) 2004 Elsevier Ltd. All rights reserved.