The sol-gel nanocrystalline thin film and aqueous chemically grown nanowires (NWs) arrays of ZnO have been used to study the room temperature photoluminescence spectra of the as-grown and annealed samples. In contrast to the thin film, the NWs show a significant change in the green emission at similar to 500 nm compared to the ultraviolet one after the heat treatments in different ambient and temperatures. From the photoluminescence results, the green emission is correlated to the native defect VznZni and the surface defect complex V-zn(-) -H2O those respectively causes the augmentation and suppression of the intensity of the emission. (C) 2009 Elsevier B.V. All rights reserved.