A solid-state conversion process for the preparation of LiNi1/3Co1/3Mn1/3O2 (NCM333) using metal oleate precursors was studied. The low melting points of metal oleate complexes result in a highly homogeneous mixture of Li-, Ni-, Co-, and Mn-oleates before calcination at a high temperature in a solid-state conversion process. The discharge capacity and capacity retention were assessed using a control sample prepared with metal acetate precursors. Cyclic voltammetry and electrochemical impedance spectroscopy showed larger cathodic and anodic peak currents and a lower charge transfer resistance for the coin cell with the cathode prepared from metal oleates than for the cell with the cathode prepared from metal acetates. The superior electrochemical properties of the NCM333 cathode prepared by the solid-state conversion process suggested in this study are attributed to the formation of a perfect R3m layered structure with a low degree of cation mixing.