Abstract Sisal-shaped hierarchical cobalt hydroxide was obtained by a simple hydrothermal method, and cobalt oxide was also easily obtained by heating the cobalt hydroxide in air. The obtained cobalt oxide possessed a similar hierarchical structure to the cobalt hydroxide. The prepared cobalt hydroxide samples were made of building blocks which took the shape of tower of Hanoi. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), field scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM) and thermogravimetry analysis (TG), which implied that various morphologies and structures of the samples could be easily obtained by changing the molar ratio of cobalt nitrate to TETA, the amount of sodium hydroxide added and reaction temperature. Furthermore, the formation mechanisms were explained. Finally, the electrochemical properties were evaluated and the prepared samples exhibited promising electrochemical applications.