Amongst solid solutions of the Li-Ni-Mn-Co-O series, LiNi1/3Mn1/3Co1/3O2 has received much attention owing to its high capacity and thermal stability. A major issue in these ordered rock salt structures is the irreversibility on the first cycle, and degree of Li+/Ni2+ cation disorder which inhibits the rate capability. To examine these factors, different synthesis methods were employed which led to LiNi1/3Mn1/3Co1/3O2 that exhibited varying degrees of cation disorder. Neutron diffraction studies were carried out on samples (LixNi1/3Mn1/3Co1/3O2, x = 1.00 → 0.04) prepared by chemical oxidation. The studies reveal that the extent of Ni2+/Li+ disorder between the 3b and 3a sites was preserved on Li extraction and re-insertion. Complete extraction of lithium to form the O1 phase was achieved in some materials. However, reformation of the O3 phase on chemical relithiation does not occur in these cases, whereas materials that only partly convert to the Ol phase exhibit complete conversion back to the O3 phase on relithiation. The differences are attributed to lithium site occupancy/stoichiometry and crystallite size effects.