A series of nanosized (Fe3-xMnx)1-δO4 (x = 0, 0.2, 0.5, and 0.8) were synthesized for elemental mercury capture from the flue gas. Cation vacancies on (Fe3-xMnx)1-δO4 can provide the active sites for elemental mercury adsorption, and Mn(4+) cations on (Fe3-xMnx)1-δO4 may be the oxidizing agents for elemental mercury oxidization. With the increase of Mn content in the spinel structure, the percents of Mn(4+) cations and cation vacancies on the surface increased. As a result, elemental mercury capture by (Fe3-xMnx)1-δO4 was obviously promoted with the increase of Mn content. (Fe2.2Mn0.8)1-δO4 showed an excellent capacity for elemental mercury capture (>1.5 mg g(-1) at 100-300 °C) in the presence of SO2 and HCl. Furthermore, (Fe2.2Mn0.8)1-δO4 with the saturation magnetization of 45.6 emu g(-1) can be separated from the fly ash using magnetic separation, leaving the fly ash essentially free of sorbent and adsorbed Hg. Therefore, nanosized (Fe2.2Mn0.8)1-δO4 may be a promising sorbent for the control of elemental mercury emission.