The redox reaction of Li 1.16 Ni 0.15 Co 0.19 Mn 0.50 O 2 positive electrode material during the charging and discharging processes was investigated by using spectroscopic methods, i.e. in situ hard X-ray absorption near edge structure (XANES) at transition metal K-edges and ex situ soft XANES at oxygen K- and transition metal L-edges. The spectral changes of constituent elements during the initial charging to 4.5 V vs. Li/Li + are quite similar to those of conventional layer-structured positive materials, such as LiNi 1/3 Mn 1/3 Co 1/3 O 2 . Ni 2+ and Co 3+ ions are fully oxidized to Ni 4+ and Co 4+ , while Mn 4+ remains unchanged. Ligand oxygen ions also take part in charge compensation. In the process of charging to 4.8 V via the plateau voltage region, no significant spectral change appears except partial reduction of Ni and Co ions in spite of lithium extraction. By discharging to 2.0 V the spectra of each element return to those of the pristine material.