LiNi1−x Co x O2 (x =0, 0.1, 0.2) cathode materials were successfully synthesized by a rheological phase reaction method with calcination time of 0.5h at 800°C. All obtained powders are pure phase with α-NaFeO2 structure (R-3m space group). The samples deliver an initial discharge capacity of 182, 199 and 189mAhg−1 (25mAg−1, 4.35–3.0V), respectively. The reaction mechanism was also discussed, which consists of a series of defect reactions. As a result of these defect reactions, the reaction of forming LiNi1−x Co x O2 takes place in high speed.