Mn/montmorillonite K 10 (Mn/MK10) prepared by impregnation method was studied to remove Hg-0 in simulated coal-fired flue gas. The samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD). Effects of manganese loading value, reaction temperature and flue gas components on Hg-0 removal efficiency were investigated. The results indicated that 4% Mn/MK10 was the optimal sample with outstanding Hg-0 removal efficiency over the temperature range of 100-400 degrees C. The characteristic analysis demonstrated that amorphous MnO2 and active oxygen were crucial for Hg-0 removal. Besides, NO had a promoting effect due to the formation of Hg(NO3)(2). The addition of only 5 ppm HCl led to excellent Hg-0 removal performance as HCl enhanced Hg-0 conversion to HgClx. The inhibition effect of SO2 could be counteracted in the presence of NO and/or HCl. The Hg-0 removal capacity showed a relative decrease when H2O (g) was added to simulated flue gas. Moreover, Hg-0 removal performance was maintained at 80-99% (NO/SO2 +/- 0.26-1.71) in simulated flue gas without HCl, which appeared to be promising in industrial application.