BACKGROUND The SO2 and NO emitted from coal-fired power plants have caused serious air pollution in China. Fe(II)EDTA complexation technology is one of the most promising processes to realize the simultaneous removal of SO2 and NO. However, Fe(II)EDTA is easily oxidized to Fe(III)EDTA, causing loss of activity, which limits its further application. To solve this problem, sodium dithionite (SD) combined with Fe(II)EDTA was used for the simultaneous removal of SO2 and NO. RESULTS Results showed that the SO2 removal efficiencies were approximate to 92-99% in all experiments, whereas the NO removal fluctuated substantially under different operating conditions. Specifically, SD can markedly improve NO removal efficiency, and the optimal Fe(II)EDTA:SD ratio was 3 mmol L-1:0.026 mol L-1. With increasing temperature, pH value, SO2 concentration or O-2 concentration, the NO removal efficiency increased first and then decreased. As the NO concentration increased, the NO removal efficiency continually decreased. Finally, based on the analysis of different ion concentrations, the main products were identified as sulfite, sulfate, ammonium, nitrite and nitrate. CONCLUSION The synergistic mechanism of SD and Fe(II)EDTA on SO2 and NO was investigated. SD can regenerate Fe(II)EDTA solution by reducing Fe(III)EDTA and Fe(II)EDTA-NO. These fundamental findings can offer valuable guidance for industrial denitrification and desulfurization by mixed Fe(II)EDTA and SD systems. (c) 2019 Society of Chemical Industry