Nano-sized LiMn2O4 spinel with well crystallized homogeneous particles (60nm) is synthesized by a resorcinol–formaldehyde route. Micro-sized LiMn2O4 spinel with micrometric particles (1μm) is prepared by a conventional solid-state reaction. These two samples are characterized by XRD, SEM, TEM, BET, and electrochemical methods. At current rate of 0.2C (1C =148mAg−1), a discharge capacity of 136mAhg−1 is obtained on the nano-sized LiMn2O4, which is higher than that of micro-sized one (103mAhg−1). Furthermore, compared to the micro-sized sample, nano-sized LiMn2O4 shows much better rate capability, i.e. a capacity of 85mAhg−1, 63% of that at 0.2C, is realized at 60C. The excellent high rate performance of nano-sized LiMn2O4 spinel may be attributed to its impurity-free nano-sized particles, higher surface area and well crystalline. The outstanding electrochemical performances demonstrate that the nano-sized LiMn2O4 spinel will be the promising cathode materials for high power lithium-ion batteries used in hybrid and electric vehicles.