Nano-Co3O4 decorated with gold nanoparticles is synthesized by a simple method of in-situ reduction of HAuCl4 by sodium citrate for energy storage application, and the effect of gold content in the product on electrochemical performance is investigated in detail. Introducing gold nanoparticles into nano-Co3O4 bulk would contribute to reduce internal resistance of charge transmission. The results show that after in-situ reduction reaction gold nanoparticles imbed uniformly into nano-Co3O4 with irregular nano particles. The gold nanoparticles decorated nano-Co3O4 exhibits specific capacitance of 681 F g(-1) higher than that of pristine Co3O4 of 368 F g(-1). It is interesting that a good cycle life with the specific capacitance retention of 83.1% is obtained after 13000 cycles at 5 A g(-1), which recovers to initial specific capacitance value when the test current density is turned to 2 A g(-1). In addition, the device of asymmetric super capacitor, assembled with gold nanoparticles decorated nano-Co3O4 as the positive electrode and activated carbon as the negative electrode, exhibits good energy density of 25 Wh kg(-1), which is comparable to the asymmetric device assembled with normal nano-Co3O4, or the symmetric device assembled just with activated carbon. (C) 2017 Elsevier B.V. All rights reserved.