Zinc oxide (ZnO) nanoparticles were produced by wire explosion process and characterized through X-ray diffraction (XRD) studies and by TEM studies. The particle size analysis indicates that they follow log-normal distribution and the mean size of the ZnO nanoparticles formed is about 44 nm. Optical band gap of ZnO is found to be 3.21 eV by UV-vis diffuse reflectance spectroscopy (DRS). The synthesized ZnO nano particles were used as photo catalyst for degradation of methylene blue (MB) in aqueous solution. Nano zinc oxide of 100 mg/L was found as the optimum quantity for UV photo degradation of 10 mg/L MB. ZnO nanoparticles were verified for its reusability. The results of the study are compared with commercial ZnO nanoparticle and with Degussa P-25 TiO2. LC-MS studies were carried out to identify the intermediates and degradation pathway. © 2017 Elsevier Ltd. All rights reserved.