Zinc oxide have been produced via a simple green method from zinc nitrate and leaf extract aqueous solutions. Prepared ZnO nanoparticles (NPs) were investigated by employing through UV-Visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission-scanning electron microscope (FE-SEM), and transmission electron microscope (TEM), respectively. The present investigation, confirmed the estimated band gap 3.51eV and the PL intensity at 402nm in visible region are dependent upon the geometrical shape and size of the ZnO NPs. The TEM micrograph and XRD pattern confirmed the hexagonal wurtzite structure of ZnO NPs. The presence of functional groups and the chemical bonding are confirmed by FTIR spectra. EDS shows that the highly pure ZnO nanostructures. Moreover, the catalytic activity of synthesized ZnO in the reduction of methylene blue was studied by UV-Vis spectroscopy. The effects of process conditions on the morphology and size of ZnO have been found from FE-SEM and TEM analyses, respectively.