A simple and facile precipitation route and its electrochemical properties were investigated by controlling the shape of crystalline ZnO nanostructures such as rods, flowers, and porous flower structures. In this paper, the morphological variation in ZnO nanostructures was achieved by varying the reaction time and precursors in the precipitation method because the precursor and reaction time ratio is important in the morphological control of ZnO nanostructures. Zinc nitrate hexahydrate and zinc acetate dehydrate were used as precursors, and refluxed at 90 degrees C with reductant for various reaction times. We then propose a growth mechanism of ZnO nanostructures on the basis of shape-control by the precipitation technique. Also, the electrochemical properties of the ZnO electrodes obtained from different precursors and reaction times were evaluated by cyclic voltammetry and galvanostatic charge/discharge measurements. (C) 2016 Elsevier B.V. All rights reserved.