Purification techniques like ozonization, chlorination and filtration have their own limitations of corresponding energy sources and harmful waste generation. However, heterogeneous photo catalysis is used for producing oxidative agent (hydroxyl radical) which has been used as an environmentally harmonious decontamination process. Such safe and low energy consumable photo catalytic system is required for purification of polluted water. Degradation of dyes is a standard method to check the photocatalytic activity of any type of photo catalyst. In this paper thioglycerol capped and uncapped ZnS nanoparticles are studied in detail for their photocatalytic activity and generation of electron hole pairs. Bromophenol blue, crystal violet and reactive red dyes were successfully photo reduced using ZnS nanoparticles after 3.0 h of irradiation. Since the photocatalytic activity depends on the generation of electron hole pairs and the existence of different phases, we have tried to correlate the optical and morphological studies with these results to understand the phenomenon of photocatalytic activity at nanoscale. Though the Ultra violet irradiation can efficiently degrade the dyes, naturally abundant solar radiation is also very effective in the mineralization of dyes. Hence, it may be a viable technique for the safe disposal of textile waste-water into the water streams. (C) 2011 Elsevier Ltd. All rights reserved.