Zinc oxide (ZnO) nanostructures were grown on A-, C- and R-plane sapphires by metal organic chemical vapor deposition (MOCVD) technique. The shape of nanostructures was greatly influenced by the underlying sapphire substrate. Vertical aligned nanowires were observed on A- and C- plane sapphires, whereas the nanopencils were grown on R-plane sapphire. A correlation between the morphological and optical properties of the nanostructures has been established, where the morphological and structural characteristics are responsible for the evolution of optical properties. The nanowires, grown on C- plane sapphires, have shown superior optical properties. Comparatively higher photo-induced wettability transition has also been observed for ZnO nanostructures on R-plane sapphire. (C) 2010 Elsevier B.V. All rights reserved.