Abstract We report the synthesis of LiNi 0.85− x Co 0.15Mn x O 2 positive electrode materials from Ni 0.85− x Co 0.15Mn x (OH) 2 and Li 2CO 3. XRD and XPS are used to study the effect of Mn-doping on the microstructures and oxidation states of the LiNi 0.85− x Co 0.15Mn x O 2 materials. The analysis shows that Mn-doping promotes the formation of a single phase. With increasing substitution of Mn ions for Ni ions, the lattice parameter a decreases, while the lattice parameters c and c/ a increase. XPS revealed that the oxidation states of Ni, Co and Mn in LiNi 0.85− x Co 0.15Mn x O 2 compounds (where x = 0.1, 0.2 and 0.4) were +2/+3, +3 and +4. The substitution of Mn ions for Ni ions induces a decrease in the average oxidation state of Ni. Because the substitution of Mn for Ni ions is complex, the extent of the changes between the lattice parameter and L M–O differ. The occupation of Ni in Li sites is affected by the ordering of Mn 4+ with Ni 2+ and Mn 4+ with Li +.