LiF-NixMn1-xO composites are prepared by the mechanical milling of LiF and NixMn1-xO (x <= 1) solid solution for 72 h. The obtained composites are examined by XRD, charge-discharge measurements, CV, and XPS. X-ray diffraction peaks of LiF-NixMn1-xO are broadened by milling. The diffraction peaks of NixMn1-xO in x < 0.5 are shifted to the higher angle by milling together with LiF. The discharge capacity and voltage of the LiF-NixMn1-xO composites changes with the molar ratio of NiO and MnO. The composite containing a large amount of Mn showed a lower discharge voltage and a larger discharge capacity. The composites containing a large amount of Ni show higher discharge voltage. The maximum discharge capacity among LiF-NixMn1-xO composites is obtained at x = 0.2, and its value is 279 mAh g(-1)for cut-off voltages of 2.0-4.8 V at 0.1 C. The XPS measurement shows that the Mn(2+)and Ni(2+)ions are oxidized to Mn(3+)and Ni(3+)ions in charging process and are reduced to Mn(2+)and Ni(2+)ions in the discharging. The oxidation and reduction process between Mn(2+)and Mn(3+)greatly contribute in the charge and discharge process of LiF-Ni0.5Mn0.5O composite.