Sulfur-impregnated and virgin activated carbons have been used in a laboratory scaled fixed-bed reactor to investigate their capability of removing mercury vapours from a gas mixture containing H2S, O-2 and moisture that is representative of the exhaust gas emissions of the geothermal power plants of the Monte Amiata field in Italy. The observed deposition of sulfur from H2S oxidation on the carbonaceous matrix increases the mercury scavenging capacity of the commercial sulfur-impregnated activated carbon and makes virgin activated carbon capable of adsorbing mercury vapours by the formation of HgS contextually to the deposition of sulfur. achieving a mercury adsorption capacity comparable to the commercial sulfur-impregnated activated carbon. This result suggests that the extremely economic virgin activated carbon can be used in this specific application, provided that a suitable carbonaceous matrix is selected to achieve a sulfur deposition rate that can guarantee a high mercury adsorption capacity. (C) 2002 CNR. Published by Elsevier Science Ltd. All rights reserved.