Abstract:Hibiscus leaf extract mediated ZnO nanoparticles have been prepared through a hydrothermal method and the effects of extract doping on the structural, optical and electronic properties of ZnO NPs were studied. The photocatalytic oxidation of methylene blue dye under visible light irradiation was used to determine the photocatalytic performance of the prepared nanoparticles. The extracted ZnO nanoparticles (R$_3$) exhibited the lowest band gap and the highest photocatalytic activity for the methylene blue dye. The photocatalytic performance of the (R$_3$) prepared ZnO nanoparticles was stable after the nanoparticles were reused five times for the oxidation of methylene blue dye.