5 V cathode material LiNi 0.5 Mn 1.5 O 4 was synthetized by a simple wet chemical reaction using acetates as precursor's materials. Cathode active materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Inductively Coupled Plasma (ICP). Electrochemical properties of active materials were evaluated through chargedischarge tests with operation voltage between 3.5 to 4.9 V at 0.3 C. The synthetized sample with high amount of Mn/Ni precursor (LMNO-1) shows a higher first discharge capacity but a faster degradation after 3 cycles. This behavior should be due to the lack of Mn substitute by Ni and therefore more significant Jahn Teller effect as shown by Raman, ICP and XPS results.