Nanoscale photocatalysts have attracted much attention due to their high surface area to volume ratios. This work investigates the photodegradation of organic contaminants using the fluorescence emission characteristics of ZnO nanoparticles (ZnO-nano) in aqueous solutions. This is accomplished by preparing nanocrystalline ZnO; the presence of organic contaminants in water is readily detected from the quenching of fluorescence observed from ZnO semiconductor films. Photolysis of ZnO thin films immersed into an aqueous system containing organic contaminants results in the degradation of the contaminants. A comprehensive study has been done involving several organic contaminants in water (like aliphatic and aromatic chloro compounds as well as some commonly used aromatic solvents) to check the suitability of ZnO-nano as an efficient photocatalyst. The ZnO nanoparticles not only serve as a better catalytic system compared to bulk ZnO and commercially available Degussa TiO2 in achieving degradation of the added contaminants, but unlike other semiconductor systems can also act as a non-specific sensor for the presence of these common contaminants in water. A total cleanup of a cocktail of contaminants in water was also achieved using the ZnO-nano. (c) 2006 Elsevier B.V. All rights reserved.