A complex absorbent containing urea and KMnO4 was used to investigate simultaneous removal of SO2, NO and Hg-0 from flue gas. By focusing on NO, SO2 and Hg-0 removal efficiencies, the influences of different types of oxidants, urea concentration, KMnO4 concentration, Hg-0 inlet concentration, initial pH, reaction temperature, SO2 and NO concentrations were systematically investigated. The results indicate that urea + KMnO4 solution cleaned up SO2 quite efficiently; the removal efficiency was more than 98%, and slightly affected by reaction conditions. NO and Hg-0 removal efficiencies depended primarily on the KMnO4 concentration. Urea concentration, reaction temperature, initial solution pH, SO2 and NO concentrations all had a strong influence on the NO removal, but had a little influence on the Hg-0 removal. The inlet concentrations of Hg-0 contributed little to the removal of NO and Hg-0. Meanwhile the optimal conditions were established, the absorption capacities of NO, SO2 and Hg-0 were calculated and the final reaction products in the solution were analyzed under the optimal conditions. This process is a promising method for the simultaneous removal of NO, SO2 and Hg-0. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.