Na_2/3Fe_1/3Mn_2/3O₂ precursor powders were successfully prepared by spray pyrolysis process. Na_2/3Fe_1/3Mn_2/3O₂ precursor powders were calcined from 700 to 1100°C. The chemical and physical properties of Na_2/3Fe_1/3Mn_2/3O₂ precursor powders and the calcined powders were characterized by powder X-ray diffraction (XRD) and a scanning electron microscope (SEM). XRD revealed that the diffraction patterns of the calcined powders were in agreement with the layered structure. The crystal phases of the calcined powders obtained from 800 to 1100°C were the phase of P2 structure (space group: P6₃/mmc). Na_2/3Fe_1/3Mn_2/3O₂ precursor powders exhibited spherical morphology with 1 µm and were nonaggregated. The morphology of Na_2/3Fe_1/3Mn_2/3O₂ precursor powders changed to irregularly morphology with 1.5 µm by calcining at 900°C. P2-Na_2/3Fe_1/3Mn_2/3O₂ cathode materials calcined at 900°C exhibited high rechargeable capacity and cycle stability. The first discharge capacity of P2-Na_2/3Fe_1/3Mn_2/3O₂ cathode materials was approximately 150 mAh g⁻¹ at a rate of 0.1 C. 93% of the initial discharge capacity was maintained after 20 cycles.