A lithium-ion battery cathode material, Li(Ni1/3Co1/3Mn1/3)O2, with excellent electrochemical properties was prepared via two-step isothermal sintering, using eutectic lithium salts (0.38LiOH·H2O–0.62LiNO3) mixed with Co, Ni, or Mn hydroxides. Based on analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM), a thermogravimetric-differential scanning calorimetric (TG–DSC) analyzer, and Fourier-transform Infrared (FT-IR), this synthetic process consists of procedures including lithium salt melting, permeation, reaction, crystalline transformation, and crystallization. Due to the lower melting point of the eutectic molten salts compared with that of the single lithium salt, a relatively mild synthetic condition (low temperature) is needed, and the product can be highly crystallized with low cation mixing, which facilitates maintenance of the precursor morphology. The electrochemical properties of the product were investigated by constant current discharge–charge and cyclic voltammetry. The results show that the initial discharge capacity is 160mhAg−1, with excellent cycling stability even after 50 cycles. We conclude that this novel eutectic molten salt method is a promising and practical approach for synthesizing cathode materials for lithium-ion batteries.