Bench- and pilot-scale studies were conducted on the simultaneous removals of SO₂, NO_x, and mercury (both Hg⁰ and Hg²⁺) from coal combustion flue gas using a limestone-based wet flue gas desulfurization (FGD) scrubber. The wet scrubber performance for multi-pollutant control was significantly enhanced with the introduction of an oxidizing additive – sodium chlorite (NaClO₂). Parametric studies investigating the effects of flue gas components (e.g., SO₂, NO), temperature, and oxidant addition rate were completed with the benchand pilot-scale experimental facilities. Various process configurations were examined to optimize the addition of sodium chlorite. Additional tests were also performed to better understand the chemistry of the oxidation and subsequent capture of the pollutants of interest.