Micro crystals of cuprous oxide (Cu2O) with different morphologies, evolving from cubes, tetrahedrons, truncated cubes and final to truncated octahedrons, were obtained on indium tin oxide (ITO) flexible substrate (polyethylene terephthalate-PET) by simply adjusting the electrochemical deposition time. We elucidated the underlying morphology evolution mechanism using the cyclic voltammogram (CV), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of Cu2O films were characterized by the ultraviolet-visible (UV-vis) spectrum, which demonstrated the band gap changing from 2.21 eV to 2.43 eV with different electrochemical deposition time owing to the quantum confinement effect. (C) 2011 Elsevier B.V. All rights reserved.