Layered Li[Ni1/3Mn1/3Al1/3−x Co x ]O2 (0≤ x ≤1/3) cathode materials are synthesized by a solvent evaporation method. Although XRD shows that Li[Ni1/3Mn1/3Al1/3]O2 has no obvious impurity phase, it has poor electrochemical properties. To improve its capability, part of Al in Li[Ni1/3Mn1/3Al1/3]O2 compound is replaced by Co in this study. The samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and charge–discharge test. The results indicate that the introduction of Co has a large influence on the morphology, structure and electrochemical performances of the samples, which become more excellent with an increase of Co content in compounds. Meanwhile, the high-temperature behavior of the samples is also investigated.