A layered Li–Ni–Ti oxide including divalent nickel and tetravalent titanium with a Ni2+/Ti4+ ratio of almost 1 was obtained by the ion exchange of a layered Na–Ni–Ti oxide precursor. By using various nickel and titanium sources, we obtained samples with different specific surface areas. Sample with larger specific surface areas had larger first charge capacities. However, a large irreversible capacity and poor cyclability were observed for all the samples when measured at room temperature. However, when we set the ambient temperature at 55°C, the cyclability improved. This suggests that the lithium diffusion rate strongly affects the electrode performance of layered Li–Ni–Ti oxide. We also employed a first-principles calculation of the LiNi0.5Ti0.5O2/Ni0.5Ti0.5O2 system to evaluate its structural and voltage characteristics.