Layer-structured cathode material for lithium ion batteries LiNi0.375Co0.25Mn0.375-xCrxO2-xFx (0 <= x < 0.1) has been synthesized from sol-gel precursors. Its structure and electrochemical properties were investigated by X-ray diffraction (XRD) and a variety of electrochemical techniques. The XRD results reveal that LiNi0.375Co0.25Mn0.375-xCrxO2-xFx has typical hexagonal structure without impurity. The Cr-F co-doped materials show higher specific discharge capacity and improved cycling performance compared with the raw materials as x in the range of 0.00-0.06. LiNi0.375Co0.25Mn0.315Cr0.06O1.94F0.06 demonstrates an initial discharge capacity of 168.5 mAh g(-1) with 20th capacity retention about 93.7%. It has been confirmed that the improved cycling performance is derived from the little increase of electrochemical impedance during the cycling. (C) 2007 Elsevier Ltd. All rights reserved.