Abstract: ZnO nanoparticles were prepared by solvothermal method by varying two different pH under harsh condition. Morphological change in ZnO nanoparticles from nanosphere to nanorods on varying pH from 11.0-10.7 was observed in Scanning Electron Micrograph (SEM). And also, the size of ZnO nanoparticle formed at 11.0 pH was found to be 54 nm. The XRD patterns of ZnO nanoparticle showed polycrystalline nature of ZnO nanoparticle. FTIR peaks at 548 and 555 cm-1 confirmed the presence of ZnO nanoparticle formation. Again UV-visible absorption spectra showed cut off wavelength at 416 nm which revealed that the size of ZnO nanoparticles were in nanodimension.