Mercury pollution is a cause for concern that requires global action. The most demonstrated and commercially available technology for mercury control is pulverized activated carbon injection. During oxy-coal combustion, the elevated concentrations of SOx, the moisture level in the flue gas, and the recirculation streams may affect the performance of activated carbons as mercury sorbents. This works evaluates mercury oxidation and capture using impregnated-activated carbons. In this study a novel aspect is considered by the application of a novel thermal desorption procedure for mercury species identification and the elucidation of the interaction mechanism. The results show oxidation efficiencies ranging from 85% to 96%. The mercury is partially retained in the solid by chemical adsorption. The formation of new mercury species HgS, HgI2, and HgO by the interaction was established.