LixNi1/3Mn2/3O2 cathode materials have been synthesized through a facile reduction-ion exchange of P3-Na2/3Ni1/3Mn2/3O2 precursors prepared by solid state (SS), spray dry (SD) and co-precipitation (CP) methods. The influence of precursor synthesis method on the structure, morphology and electrochemical performances of LixNi1/3Mn2/3O2 has been investigated. X-ray diffraction (XRD) results of LixNi1/3Mn2/3O2 demonstrate that all the samples exhibit similar XRD patterns as those of Lithium-excess layered cathode materials. Scanning Electron Microscope (SEM) images and Brunauer-Emment-Teller (BET) results present that the particle size, particle aggregation and surface area changed greatly with the precursor synthesis method. Galvanostatic charge-discharge results show that Li1.41Ni0.32Mn0.66O2+δ cathode prepared from co-precipitation precursor exhibited high first discharge capacity of ca. 270 mAhg−1 with an initial cycle efficiency as high as 98%. The discharge capacity of Li1.41Ni0.32Mn0.66O2+δ cathode after 30 cycles is over 250 mAhg−1 and it can deliver a discharge capacity roughly 210 mAhg−1 at a current density of 500 mAg−1 (2C rate). Also, it was found that Li1.41Ni0.32Mn0.66O2+δ cathode shows enhanced electrochemical performance over the Li2/3Ni1/3Mn2/3O2 cathode with respect to reversible capacity and rate capability.