LiNi0.5Mn0.5O2, a promising cathode material for lithium-ion batteries, is synthesized by a novel solution-combustion procedure using acenaphthene as a fuel. The powder X-ray diffraction (XRD) pattern of the product shows a hexagonal cell with a =2.8955Å and c =14.1484Å. Electron microscopy investigations indicate that the particles are of sub-micrometer size. The product delivers an initial discharge capacity of 161mAhg−1 between 2.5 and 4.6V at a 0.1C rate and could be subjected to more than 50 cycles. The electrochemical activity is corroborated with cyclic voltammetric (CV) and electrochemical impedance data. The preparative procedure presents advantages such as a low cation mixing, sub-micron particles and phase purity.