ZnO thin films and nanostructures have been grown on ITO and Si (100) substrates with varying concentration of electrolyte by electrodeposition at low temperatures. The structural analysis showed an evolution of directional growth along (002) crystallographic plane with the change of electrolyte concentrations. The peak position of defect-related bands depends upon the electrolyte concentration, and at higher molar concentration the dominant luminescent center corresponds to green emission. Furthermore, the nature of substrate also contributes to the origin of the different luminescent center. These results demonstrate that the electrolyte concentration and choice of substrate can tune the optical properties of ZnO thin films and nanostructures. (c) 2013 Elsevier B.V. All rights reserved.