High voltage spinel LiNi0.5Mn1.5O4 is considered as one of the most promising cathode materials for Li- ion batteries. LiNi0.5Mn1.5O4 can adopt two different cubic cells: an ordered spinel structure, where Ni and Mn occupy distinct crystallographic sites (S.G. P4332) or a disordered one (S.G. Fd-3m), where Ni and Mn are randomly distributed in the same site. These structural differences affect the electrochemical properties from the galvanostatic curves shape to the cycling life. Very recently, based on Raman spectroscopy measurements and electrochemical characterizations, we evidenced a composition domain of the ordered spinel phase, between LiNi0.4Mn1.6O4 to LiNi0.5Mn1.5O4, when samples are prepared at 700°C. Our aim is to finelly determine the limits (synthesis temperature and composition), the ordering degree, and to determine how it affects the electrochemical properties.