A LiCoO 2 precursor is prepared by a complex formation reaction in a solution that contains LiOH, Co(NO 3 ) 2 , and humic acid it is used as a cathode for a lithium-ion rechargeable battery. Layered LiCoO 2 powders are prepared in air at 700 or 850°C after preheating the precursor at 350 and 450°C, respectively. X-ray diffraction spectra of the powders display a high intensity (003) peak and two low intensity (104) and (101) peaks. This indicates that the powders are well crystallized. Cyclic voltammetry, a galvanostatic charge/discharge experiment, and impedance spectroscopy are used to characterize the LiCoO 2 electrode in a 1 M LiClO 4 /propylene carbonate electrolyte solution during the intercalation/de-intercalation of lithium ions through the electrode. The voltammogram recorded at a scan rate of 0.01 mV s −1 shows a set of redox waves that are caused by the de-intercalation/intercalation of lithium ions through the electrode. A cell, composed of u LiCoO 2 cathode and a Li anode, shows an initial discharge specific capacity of 1 12.5 mA h g −1 at a current density of 1 mA cm −2 (43.25 mA g −1 ) between 3.6 and 4.2 V vs. Li/Li + electrode. 100 charge/discharge cycles were achieved for a cell composed of a LiCoO 2 , cathode and graphite (MCMB 6–28) anode separated by Cellgard 2300. X-ray diffraction, charge/discharge, and cyclic voltammetric data shows that there is only a single phase reaction below 4.3 V during charge/discharge for a electrode prepared at 700°C. The diffusivity of lithium ions. D Li + , as determined by AC. impedance, is 5.2 × 10 −12 m 2 s −1 .