ZnO nanoparticles were synthesized by sol-gel method and characterized by XRD, SEM, EDX and BET analysis. These nanoparticles were tested for its antibacterial activity against the clinical pathogens Escheria coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Staphylococcus aureus using disc well diffusion method. Positive activity was observed against Pseudomonas aeruginosa and Staphylococcus aureus. The catalyst nanoparticles were also used for the removal of toxic organic pollutants such as, dye acid blue 113 under UV irradiation in a batch reactor. The different operational parameters such as the initial concentration of the dye, weight of photo catalyst and pH on the photo catalytic degradation of the dye were investigated. The optimum catalyst loading was found to be 2.0 g L- 1. It was noticed that the degradation of the dye was found to be more pronounced in neutral medium.