Gas-phase oxidation of elemental mercury (Hg-0) from flue gas by simulated electrostatic precipitators (ESP) electric field was explored in this paper. In order to enhance the removal efficiency of Hg-0 by ESP electric filed, a novel discharge activation reactor was designed and employed. The influence of HCl concentration, temperature, fly ash, and flue gas components on the Hg-0 removal were also considered, respectively. The Hg-0 removal efficiency increased with the increase of HCl concentration, temperature and discharge voltage. It has also been found that O-2, H2O and fly ash showed a light promotion on the removal of Hg-0 while NO and SO2 had a slight inhibition effect on Hg-0 oxidation. Furthermore, the novel discharge activation reactor could improve the generation of reactive chemical species, such as Cl- or Cl-2, which facilitated the mercury removal. At the reaction temperature of 413 K, about 60% Hg-0 could be removed from simulated flue gas under 25.0 kV in presence of 10.0 ppmv HCl. When the novel discharge activation reactor was used, the Hg-0 removal efficiency increased to about 80% at the same experimental conditions. It appeared to be a promising technique to enhance the removal of Hg-0 by ESP. (C) 2016 Elsevier Ltd. All rights reserved.