Iron oxides have attracted a great deal of attention among specialists because of their multivalent oxidation states. The β-iron oxide nanoparticles have been synthesized by adding a Eucalyptus globulus leaf extract into the aqueous solution of ferric chloride. The synthesized nanoparticles were characterized by Ultra Violet - Visible spectrum (UV-Vis), X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Fourier Transform Infra Red spectroscopy (FT-IR). TEM and SEM image shows the nanostructures of prepared iron oxide nanoparticles. The XRD and UV-Vis spectrum confirmed the prepared iron oxide nanoparticles β in phase. [DOI: 10.1380/ejssnt.2014.363]