Zinc oxide nanoparticles have been synthesized by a sol-gel microwave assisted method using either ethylene glycol (ZnO-EG) or poly ethylene glycol ethanolic solution (ZnO-PEG) as dispersing media. The nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared. X-ray analysis revealed a hexagonal phase structure of both zinc oxides. The average crystallite size calculated from Scherrer equation was 27 nm and 53 nm in good agreement with 24 nm and 55 nm microscopic results for ZnO-EG and ZnO-PEG, respectively. The catalytic activity of the as-prepared nanoparticles was compared by the photodegradation of 2-nitrophenol under UVC. The effect of various parameters such as pH, catalyst weight, and pollutant concentration on the percent degradation was investigated. Best optimization was pH=7, 0.06g of nanoparticles weight, and 10 mg.L-1 pollutant concentration. Furthermore, pseudo first order kinetic based on Langmuir–Hinshelwood (L–H) model was proposed for degradation reactions and experimental data were in good agreement with this model.