The current research work focuses on the catalytic activity of ZrO2 nanoparticles (NPs). ZrO2 NPs exhibits excellent sonocatalytic and photocatalytic activity against decolorization of both cation dye (Victoria Blue) and anionic dye (Direct Red 81). Well crystalline monodispersed ZrO2 NPs have been synthesized and characterized by using UV-visible spectroscopy, Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transmission Infrared Spectroscopy (FTIR). Effect of catalytic activity of ZrO2 NPs on dye has been visualized by analyzing the change in absorbance of dye under UV-spectrophotometer. The degradation of the organic dyes has been calculated by monitoring the decrease in concentration of the dye w.r.t original concentration of dye. The effects of operating parameters such as catalyst dosage, pH and dye initial concentration have also been investigated. The enhanced degradation capacity of ZrO2 NPs in the presence of ultrasonic irradiations than in the presence of UV-visible irradiation has been discussed. The degradation of both the dyes follows pseudo-first order kinetics. The rate constants for both sonocatalysis and photocatalysis have successfully established and reusability tests have also been done to ensure the stability of the used catalysts. Rate constant for sonocatalysis is very high as compared to photocatalysis. (C) 2015 Elsevier B.V. All rights reserved.