Spinel LiMn 2 O 4 crystal with the grain sizes of about 15 nm is firstly synthesized by hydrothermal route at 180 °C using MnO 2 as a precursor. The LiMn 2 O 4 powders synthesized by hydrothermal technique and sol–gel reaction were investigated by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The LiMn 2 O 4 samples were used as cathode materials for lithium-ion battery, whose electrochemical properties were investigated. The results show that the sample obtained by hydrothermal route has higher capacity than that prepared by sol–gel method.