The wettability control of solid surfaces is important from the aspects of both science and technology. Herein, we report a surface-modification-induced hydrophilicity to superhydrophobicity transition on well-aligned single-crystalline ZnO nanorod array films (ZnO-NAFs). The ZnONAFs were prepared from solution by a hydrothermal method and were characterized by X-ray diffraction and scanning electron microscopy. The surface of transparent ZnO-NAFs was highly hydrophilic with a water contact angle of 9.6 +/- 0.8 degrees. However, after being exposed to octadecanethiol solution, the surfaces of the ZnO-NAFs became superhydrophobic with a water contact angle of 156.2 +/- 1.8 degrees. The present work offers a technique that has great potentials for preparing two-dimensional micro-pattems with a high wettability contrast for water. (c) 2007 Elsevier B.V. All rights reserved.