Array of Li4Ti5O12 nanoparticles was synthesized via a hydrothermal reaction. Hydrogen titanate nanotubes were prepared by an alkali-hydrothermal reaction and the hydrogen titanate was converted to Li4Ti5O12 by a hydrothermal treatment in an LiOH solution. The products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and their electrochemical performances were tested galvanostatically. Formation of the array of Li4Ti5O12 nanoparticle and TiO2 (anatase) could be confirmed by the analyses and a typical electrochemical behavior of Li4Ti5O12 and TiO2 was shown in the galvanostatic cycling.