The behavior of mercury (Hg) species during thermal cogeneration was analyzed in a 10MWh solid refuse fuel (SRF) utility boiler using a selective non-catalytic reduction unit, semi-dry reactor, and fabric filter with activated carbon injection for air pollution control from the facility. The annual Hg inflow into this facility is 24.2 (from 9.2 to 33.3) kg. The Hg species in flue-gas at inlet and outlet of the air pollution control devices (APCDs) were observed to be a mixture of 14.4 μg-Hg/Sm3 of particulate mercury, 2.6 μg-Hg/Sm3 of oxidized mercury, and 15.6 μg-Hg/Sm3 of elemental mercury and another mixture of 0.0 of particulate mercury, 0.3 of oxidized mercury, and 11.0 of elemental mercury, respectively. Elemental mercury was the major component in the combustion residue. In the emission assessment, the mass distribution of Hg of fly ash, bottom ash, and stack emission was determined as 67% (16.2 kg/yr), 2.0% (0.47 kg/yr) and 31% (7.5 kg/yr), respectively. Although elemental mercury was captured by APCDs configuration, it is best to chemically capture the air-emission mercury. Evaluation of Hg stability was tested for the fly ash by sequential extraction procedure method.