Abstract The phase evolution and the sintering process of Co/Li 2CO 3 mixtures following thermal treatment at 1200 °C in air were evaluated. In the dynamic step of the thermal treatment, Co 3O 4 and LiCoO 2 were obtained and the densification and grain size of lithiated samples were higher than those of pure Co. In the isothermal step at 1200 °C, decomposition of LiCoO 2 and diffusion of lithium ions into CoO with formation of Li x Co 1 − x O solid solution were denoted, and after 40 h of isothermal treatment almost all LiCoO 2 decomposed. The sintering constant n varied from 0.27 to 0.37, which suggested that grain-boundary diffusion was the primary mechanism for material transport. For all the compositions considerable morphological changes took place during thermal treatment.