Highly c-axis oriented ZnO nanowires' arrays were grown on glass substrates using an aqueous solution approach, in which the growth temperature does not exceed 95 degrees C in any step of the synthesis. Both their photocatalytic and wetting properties were studied upon ultraviolet (UV) light irradiation. It is revealed that ZnO nanowires' arrays show advanced photocatalytic activity, along with a remarkable reversible photo-induced transition from hydrophobic to super-hydrophilic under UV light exposure, reaching a nearly zero contact angle in short time. The capability to control the morphological characteristics of ZnO nanowires via the deposition of an amorphous seed layer is discussed, which can be significant for self-cleaning applications. (C) 2011 Elsevier B.V. All rights reserved.