Nano-structured cobalt oxides (Co3O4) with various morphologies (sheet-like, herbs-like and net-like) have been in situ synthesized on the surface of nickel foam via a facile solvothermal method. Ethanol, ethylene glycol (EG) and glycerol (GR) were used to investigate the effects of solvent on the size and morphology of nanocrystals in detail. The possible formation mechanisms have been proposed that the dielectric constants and viscosity of solvents is speculated to be the main factor to determine the morphology of Co3O4 crystal. Applied for supercapacitor, the fabricated Co3O4 electrodes show the desired properties of macroporosity, allowing facile electrolyte flow and fast electrochemical reaction kinetics. Results show that the nanonet-like Co3O4 electrode synthesized in glycerol solvothermal condition has the highest capacitance (1063 Fig at a discharge current density of 10 mA/cm(2)), and good rate capability, excellent electrochemical stability (90.8% retention after 1000 cycles). The enhanced electrochemical performance is attributed to the open and ultrathin nanostructure of net-like Co3O4 electrode, which facilitates the electron transport. The findings in this work demonstrate the importance of solvents used for solvothermal reaction, and are meaningful in understanding the self-assembly process of various Co3O4 nanostructures. (C) 2013 Elsevier Ltd. All rights reserved.