Novel large-scale Co3O4 nanoflower (NF) structures on Ni foam are prepared for the first time via a general two-step synthesis. Through a controllable solvothermal process and hereafter with a post-calcination process in air, the NFs have been grown firmly on Ni foam, which is convenient for the construction of supercapacitors without any extra electrode preparation process. The pore sizes and the amount of Co3O4 NFs can be tuned through different post-calcination and solvothermal conditions, respectively. The electrochemical properties of the NFs are tested by cyclic voltammetry, galvanostatic charge-discharge in 6.0 M KOH solution. The results show that the NFs can have a specific capacitance of 1936.7 F g(-1) at a current density of 0.2 A g(-1) and a capacity retention of 78.2% after 1000 cycles at a current density of 3 A g(-1) (1309.4 F g(-1)). The Co3O4 NFs grown on Ni foam with large area and superior electrochemical performance have great potential application in supercapacitors. (C) 2011 Elsevier Ltd. All rights reserved.