Hierarchical Co3O4 nanostructure is synthesized via a self-assembled process in molten hydroxides. The morphologies, crystal structures and the phase transformation processes are analyzed by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. As an anode material for lithium ion batteries, the hierarchical Co3O4 exhibit an initial capacity of 1336mAhg−1 and a stable capacity of 680mAhg−1 over 50 cycles. More importantly, high rate capability is obtained at different current densities between 140 and 1120mAg−1. The improved electrochemical performance of Co3O4 could be attributed to the unique hierarchical nanostructure.