An LiMnPO4/C composite material with ordered olivine structure was synthesized by a microwave-assisted solvothermal process in 2:5 (v/v) water-diethylene glycol mixed solvents at 190°C for 5min. The sample was characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. The prepared LiMnPO4/C particles exhibited an irregular flaky form coated with a uniform carbon layer (approximately 2–3nm thick). The prepared LiMnPO4/C composite exhibited a discharge capacity of 131.4 and 85.2 mAh·g−1 at 0.1C and 5C, respectively. It delivered a discharge capacity of 109.2 mAh·g−1 with a capacity retention ratio of approximately 99% after 50 cycles at 1C. Furthermore, this microwave-assisted solvothermal approach led to a significant decrease in the reaction time as compared to conventional hydrothermal/ solvothermal processes.