The A-site La 0 . 3 3 NbO 3 perovskite was prepared by a solid-state reaction at high temperature. A superstructure was observed in both the XRD and electron diffraction patterns of La 0 . 3 3 NbO 3 , which is related to the ordering of La 3 + ions and vacancies in the A sites. The La 0 . 3 3 NbO 3 was used as the electrode material in lithium cells. Approximately 0.67 lithiums can be electrochemically inserted per La 0 . 3 3 NbO 3 formula, which confirms the structural analysis. The kinetic process of lithium insertion/extraction in a La 0 . 3 3 NbO 3 electrode was determined by electrochemical impedance spectroscopy (EIS). The charge-transfer resistance (R C T ) decreases and the diffusion coefficient increases with lithium insertion into La 0 . 3 3 NbO 3 structure.