LiCoO2 powders were synthesized by the sol-gel process at various temperatures using acrylic acid as a chelating agent and their structural and electrochemical properties were systematically investigated by X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), Electrochemical voltage spectroscopy (EVS), cyclic voltammetry (CV), and galvanostatic charge/discharge experiments. In this study, the gel-derived LiCoO2 samples calcined at 600 degrees C or above were found to be a well-developed layered high temperature-LiCoO2 (HT-LiCoO2). In the EVS of all the gel-derived HT-LiCoO2 samples, the peak potential separation of 10 mV was observed regardless of the calcination temperature, indicating that these samples have basically the same thermodynamic reversibility for intercalation/deintercalation of Li ions. The change of the main peak potentials and currents in cyclic voltammograms with increasing calcination temperature could be explained by the effect of particle size.