Mn3O4/double-walled carbon nanotube nanocomposites for supercapacitor were successfully synthesized via a facile and low-cost chemical precipitation route, using potassium permanganate as precursor and hydrazine hydrate as reductant at room temperature. The nanocomposites were characterized by Xray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier Transform infrared spectroscopy and Brunauer-EmmettTeller surface area measurements, respectively. The Mn3O4 nanoparticles were highly dispersed on the surface of double -walled carbon nanotubes. Cyclic voltammetry and galvanostatic charge/discharge technique were performed for the Mn3O4/double-walled carbon nanotube nanocomposites in 1 M Na2SO4 aqueous solutions; the specific capacitance of Mn3O4/double-walled carbon nanotube nanocomposites (26.58 wt% Mn304) was about 1080Fr1 at the current density of 15 Arl with a long life time, owing to the high power density of Mn3O4 nanoparticles and the large surface area, excellent catalysis, good conductivity, and high stability of the double -walled carbon nanotubes. (C)2017 Elsevier Ltd. All rights reserved.