A nano-wired Co3O4 was successfully synthesized by a hydrothermal method in combination with subsequent calcination process. An asymmetric supercapacitor based on the Co3O4 as the positive electrode and the activated carbon (AC) as the negative electrode with a 6 M KOH solution as electrolyte was assembled. The electrochemical performance of the asymmetric supercapacitor was investigated by means of cyclic voltammetry and galvanostatic charge-discharge tests. A specific capacitance of 81 F g(-1) as well as specific energy density of 24.9 W h kg(-1) was obtained for the asymmetric supercapacitor within the voltage range of 0-1.5 V. The supercapacitor also exhibited a good cycling performance and kept 90% of initial capacity after 5000 cycles. (C) 2013 Elsevier B.V. All rights reserved.