A spinel LiMn2O4/C composite was synthesized by hydrothermally treating a precursor of manganese oxide/carbon (MO/C) composite in 0.1M LiOH solution at 180°C for 24h, where the precursor was prepared by reducing potassium permanganate with acetylene black (AB). The AB in the precursor serves as the reducing agent to synthesize the LiMn2O4 during the hydrothermal process; the excess of AB remains in the hydrothermal product, forming the LiMn2O4/C composite, where the remaining AB helps to improve the electronic conductivity of the composite. The contact between LiMn2O4 and C in our composite is better than that in the physically mixed LiMn2O4/C material. The electrochemical performance of the LiMn2O4/C composite was investigated; the material delivered a high capacity of 83mAhg−1 and remained 92% of its initial capacity after 200 cycles at a current density of 2Ag−1, indicating its excellent rate capability as well as good cyclic performance.