Nano-sized lithium manganese phosphate (LiMnPO4) is successfully prepared using a mild solvothermal method in ethylene glycol solvent. The particle size, observed by Scanning Electron Microscopy (SEM), is approximately 100 nm using C6H5COOLi as the starting material. Further TEM characterization reveals that the decomposition of benzoyloxy in this lithium salt leads to a favorable configuration, with LiMnPO4 particles embedded in carbon and a distinct in situ carbon layer formed even on partial particles. Using subsequent heat-treatment with a certain amount of sucrose, LiMnPO4/C composites that display a good two-phase plateau during the discharge process can be formed, with a specific capacity over 130 mAh g−1 at 0.1 C.