Sun light assisted photocatalytic decontamination of sulfur mustard (HD) was studied by using ZnO nanoparticles and the data was compared with those carried out in the presence of UVA and visible light radiation. In the presence of Sun light, 100% of HD was decontaminated in 12 h. Whereas, in the presence of UVA light 90%, and in visible light 80% of HD was decontaminated in 12 h. GC-MS data indicated the formation of thiodiglycol, hemisulfur mustard, divinyl sulfide, 2-chloro ethyl vinyl sulfide, etc., on the surface of ZnO nanoparticles in the case of dark and visible light irradiation experiments. However, in Sun light and UVA light irradiation experiments, GC-MS data indicated the formation of HD sulfoxide, HD sulfone, 1,3-dithiane, 2-chloro ethanol, acetaldehyde, carbon dioxide, etc. along with hydrolysis and elimination products. Under the illumination of visible light and in dark hydrolysis, elimination and surface complexation reactions have contributed to decontamination of HD. Whereas, in the presence of Sun light and UVA light, photocatalytic reactions like C-S bond cleavage, oxidation of C, S atoms were observed to have contributed to decontamination of HD in addition to hydrolysis and elimination reactions. © 2011 Elsevier B.V. All rights reserved.