Cerium-doped Zinc Oxide nanoparticles were prepared with co-precipitation method. X-Ray diffraction (XRD) analysis shows sharp peaks conforming the crystalline nature of prepared particles. Crystallite size was found from XRD peaks. A Field Emission Scanning Electron Microscope (FESEM) was used to see the particles and hexagonal shape. Spectroscopic properties were studied using a Fourier Transform-Infra Red (FTIR) spectrometer and Raman spectrometer. Optical properties were studied using a Diffuse Reflectance Ultraviolet Visible (DRS UV–VIS), spectrophotometer. Band gap of doped particles reduces as doping concentration increases. Reduced band gap of Cerium doped particles makes them a good catalyst. There are many organic dyes which are used as coloring agents by industries like textile, printing, etc. These industries releaseharm full pollutants into water bodies, which effect human and aquatic life. Prepared Cerium-doped ZnO nanoparticles have proved to photodegrade Methylene Blue. Undoped ZnO nanoparticles decolorized the solution in 210 min with 81.93% efficiency. Ce (0.03 wt%) doped ZnO nanoparticles decolorized the solution in 120 min with 92.62% efficiency.