The nano-structured manganese oxide was synthesized by a simple hydrothermal route at a very low temperature of 60 degrees C using potassium permanganate as oxidant and ethanol as reductant. The structure and surface morphology of the as-prepared manganese oxide were characterized by means of X-ray diffraction and scanning electron microscopy. The obtained manganese oxide was of amorphous and spherical with a particle size of about 100 nm. The capacitive characteristics of the nano-structured manganese oxide electrodes were investigated by means of cyclic voltammetry and galvanostatic charge-discharge cycling in 1 M Na2SO4. The manganese oxide exhibited not only a maximum specific capacitance of 198 Fg(-1), but also excellent rate capability and good cycle stability. (C) 2012 Elsevier Ltd. All rights reserved.