In this paper, spinet Li4Mn5O12 electrode material was prepared by a citric-acid-assisted combustion method. The structure and morphology of Li4Mn5O12 were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM) and electron tunneling electron microscopy (TEM). The results showed that the Li4Mn5O12 powders were nano-sized particles. XRD Rietveld refinement gives the crystal structure of prepared sample. Electrochemical performance of Li4Mn5O12 electrode was studied by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge measurements. Li4Mn5O12/Li4Mn5O12 symmetric supercapacitor was fabricated at the first time. The maximum specific capacitance was 69 F g(-1) in the potential range of 0-1.4 V in 1 mol L-1 Li2SO4 electrolyte. The energy density was 67.6 W h kg(-1) at a power density of 493.8 W kg(-1) based on the total weight of the active electrode materials. (C) 2010 Elsevier B.V. All rights reserved.