Nanoparticles of lithium manganese oxide (LiMn2O4) spinel oxides have been synthesized from aqueous solutions of metal acetate containing citric acid as a chelating agent by a sol–gel method. The influence of calcination temperature on the physicochemical properties of LiMn2O4 powders in air atmosphere has been analyzed by means of X-ray diffraction (XRD) and electron microscopic techniques. The thermal behavior of the material has been examined by thermogravimetry (TG) and differential thermal analysis (DTA). Two sharp and well-defined peaks obtained from cyclic voltammetry of Li/1M LiPF6-EC/DEC electrolyte/LiMn2O4 cell reveal that the LiMn2O4 particles are highly crystalline and insertion–extraction mechanism occur at two stages in the 4V region.