Sodium ferrite, Na2O . 1.5Fe(2)O(3), is studied as a novel active material for the negative electrodes of lithium-ion batteries. This material is prepared by decomposing a stoichiometric mixture of sodium carbonate and ferric oxide in air at 900 degrees C for 24 h. The insertion and extraction of lithium ions is examined by means of a constant-current cycling technique and cyclic voltammetry using a Li/Na2O . 1.5Fe(2)O(3) cell. X-ray diffraction is used to examine the stability of the structure of the sodium ferrite electrodes during lithium insertion and extraction. The results show that the material has excellent cyclic performance and a high reversible capacity (360 mA h g(-1))in a 1 M LiClO4 + PC electrolyte solution.