The ability of three sorbents (activated carbon, char, and mordenite) to adsorb Hg is determined using simulated flue gas containing 10-15 mu g/m(3) in a laboratory-scale, fixed-bed adsorption system. The adsorption performance of the three sorbents is compared by adsorption rate rather than adsorption capacity. The effect of temperature, sorbent loading, Hg concentration, and acid gases such as NO and SO2 on the adsorption rate is investigated and presented in this paper. The Hg adsorption rate is in the range of 3000-3900 ng/h for all three sorbents and increases with temperature, Hg concentration, and acid gas concentration. Temperature is the major factor affecting the Hg adsorption rate on activated carbon and char while the rate of Hg adsorption on the zeolite sorbent is more strongly effected by the Hg concentration in the flue gas stream.