LiNi 0.5 Co 0.5 O 2 cathode materials were synthesized by a solid-state reaction method at 800°C using Li 2 CO 3 , LiOH·H 2 O; NiO, NiCO 3 ; CoCO 3 , or Co 3 O 4 as the sources of Li, Ni, and Co, respectively. The electrochemical properties of the synthesized samples were then investigated. The structure of the synthesized LiNi 0.5 Co 0.5 O 2 was analyzed, and the microstructures of the samples were observed. The curves of voltage vs. x in Li x Ni 0.5 Co 0.5 O 2 for first charge–discharge and intercalated and deintercalated Li quantity Δx were studied. Destruction of unstable 3b sites and phase transitions were discussed from the first and second charge–discharge curves of voltage vs. x in Li x Ni 0.5 Co 0.5 O 2 . The LiNi 0.5 Co 0.5 O 2 sample synthesized from Li 2 CO 3 , NiCO 3 and Co 3 O 4 has the largest first discharge capacity (142mAh/g). The LiNi 0.5 Co 0.5 O 2 sample synthesized from Li 2 CO 3 , NiO and Co 3 O 4 has a relatively large first discharge capacity (141mAh/g) and the smallest capacity deterioration rate (4.6mAh/g/cycle).