We had developed a facile synthetic route of Co3O4 crystals with different morphologies via one step template-free hydrothermal method. The phase and composition of the Co3O4 were investigated by X-ray powder diffraction and Raman spectrum. The morphology and structure of the synthesized samples were characterized by scanning electron microscopy and transmission electron microscopy. The H2O2 played a crucial role in morphological control of Co3O4 nanostructures. It only obtained Co-based precursor in the absence of H2O2. On the contrary, the Co3O4 with different morphologies including nanoparticles, nano-discs and well-defined octahedral nanostructures were synthesized in the presence of H2O2. In addition, the optical property of the obtained Co3O4 samples was investigated by UV-vis spectra. (C) 2015 Published by Elsevier Ltd.