In this study, the synthesis of lithium manganese oxide (LiMn₂O₄) with spinel structure by a supercritical-hydrothermal (SH) accelerated solid state reaction (SSR) route is reported. The effects of reaction pressure, reaction temperature, calcination temperature and calcination time on the purity, particle morphology and electrochemical properties of the prepared LiMn₂O₄ materials were studied experimentally. The structure, morphology and electrochemical performance of LiMn₂O₄ were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and charge and discharge test, respectively. Results showed that the LiMn₂O₄ materials prepared by a supercritical hydrothermal process under conditions of 400 ^oC and 30 Mpa followed by heat treatment at 700 ^oC for 3 h exhibited good crystallinity, uniform size distribution and good electrochemical performance, delivering an initial specific capacity of 123 mAh/g at a rate of 0.1 C and exhibiting good cycle performance.