Grain shape and orientation control on Cu2O films were achieved on ITO substrates via the electrochemical route by changing the solution pH. The film orientation was delicately tuned in sequence from the [100] direction to [110] and [111] direction with the solution pH rising from 9.0 to 10.5 and 12.3. The surface grains of the Cu2O film showed shape evolution associated with the solution pH and the orientation. Measurements on the as-prepared Cu2O films demonstrated that the flat band potential and the band gap energy depend on the grain shapes and the orientation. The evolution mechanisms of the grain shape and the orientation as well as their relationship to the semiconductor properties were elucidated based on the crystal structure and the coordination chemistry. (C) 2015 Elsevier Ltd. All rights reserved.