A series of LiMgxMn2-xO4 (x ≤ 0.20) cathode materials were rapidly synthesized at a low temperature of 500°C for 1h by a solid-state combustion process. The morphologies and crystal structures of LiMgxMn2-xO4 were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. All LiMgxMn2-xO4 samples exhibited a single phase LiMn2O4 spinel structure with good crystallinity. The linear decrease of the lattice parameters with the increase of Mg-doping content could suggest that Mg2+ ions had put into the spinel LiMn2O4 lattice substituting for Mn3+. The effect of Mg2+ ions on the electrochemical performance of LiMgxMn2-xO4 was investigated by galvanostatic charge-discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the Mg-doped LiMn2O4 possessed better cycling stability, for example, a capacity retention of 93.2% for LiMg0.08Mn1.92O4 after 150 cycles at 0.2C.