Abstract: The adsorption capacity for vapor-phase elemental mercury (Hg⁰) of residual carbon separated from fly ash was investigated in an attempt for the control of elemental mercury emissions from combustion processes. At low mercury concentrations (<250 μg/m³), the adsorption capacity difference of residual carbon to commercial activated carbon is not significantly, but the mercury sorption capacity of commercial activated carbon increase significantly at high mercury concentrations. The mercury sorption capacity of residual carbon was also found to be source dependent. The isotherms of residual carbon were similar to those classified as Type Ⅱ with distinctness different in concave. But commercial activated carbon was more like those classified as Type Ⅲ. Static experiments reveal that prime sites which enhance the mercury adsorption exist in the surface of carbon. Due to the relatively low production costs, these residual carbons would likely be considerably more cost-effective for the removing of mercury from combustion flue gases than other technologies.