Iron oxide nanoparticles were synthesized using a biological approach using the Beauveria bassiana fungus. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), scanning analysis (SEM), and atomic energy microscope (AFM). The iron nanoparticles in an average grain size of ~ 39 nm. The topography and features of the surface show that there are ripples distributed regularly and homogeneously on the surface and that the deposited film is regular. The optical properties of iron oxide were studied using UV/Vis spectroscopy, and it was found that the absorbance gradually decreases as we approach the visible light region, starting from its peak at short wavelengths, where the surface plasmon resonance was recorded, which showed the absorbance at the UV wavelength at (282 nm), and the absorbance is at its maximum at high energies (short wavelengths), then decreases with increasing wavelength to reach its lowest value in the visible region of the spectrum, and for this reason the absorbance decreases with increasing wavelength, where the energy gap value is (2.5 electron volts). The FTIR spectrum showed functional groups have been recorded in a range These results confirm the presence of the fungal extract belonging to the fungus Beauveria bassiana. The vibrations in the phenolic compounds are responsible for the interaction process with the salts of the basic materials used in the preparation