Manganese oxide with high tap density was prepared by decomposition of spherical manganese carbonate, and then LiMn2O4 cathode materials were synthesized by solid-state reaction between the manganese oxide and lithium carbonate. Structure and properties of the samples were determined by X-ray diffraction, Brunauer–Emmer–Teller surface area analysis, scanning electron microscope and electrochemical measurements. With increase of the decomposition temperature from 350°C to 900°C, the tap density of the manganese oxide rises from 0.91gcm−3 to 2.06gcm−3. Compared with the LiMn2O4 cathode made from chemical manganese dioxide or electrolytic manganese dioxide, the LiMn2O4 made from manganese oxide of this work has a larger tap density (2.53gcm−3), and better electrochemical performances with an initial discharge capacity of 117mAhg−1, a capacity retention of 93.5% at the 15th cycle and an irreversible capacity loss of 2.24% after storage at room temperature for 28 days.