The nickel-manganese compounds were synthesized by redox reactions in aqueous solutions using potassium permanganate as an oxidizing agent at ambient temperature. Also, a layered Li-Ni-Mn-O system was synthesized by using a nickel-manganese compound as precursor for electrode materials. X-ray diffraction patterns of the lithiated Li1.296Ni0.056Mn0.648O2 Sample were indexed to a layered structure based on hexagonal alpha-NaFeO2 (space group: R-3m, 166) with signs of monoclinic-related peaks indicating the existence of monoclinic, Li2MnO3 phase. The lithiated Li1.296Ni0.056Mn0.648O2 electrode provides the initial discharge capacity of 108 mAh g(-1) and the maximum discharge capacity of 192 mAh g(-1) between 2.0 and 4.8 V versus Li/Li+ at 0.2 mA cm(-2). (c) 2006 Elsevier B.V. All rights reserved.