A facile and simple approach has been described for the synthesis of magnetite nanoparticles and iron oxyhydroxide nanorods using biogenic polyamines. At room temperature, highly crystalline magnetite particles with average size of 44 ± 2 and 37 ± 1 nm were synthesized with spermine and spermidine, respectively. The formation of nanoparticles was characterized with TEM, HRTEM, XPS and SQUID. The magnetite nanoparticles formed by the biogenic polyamines exhibits ferrimagnetic behavior at 300 K. When the reaction was carried out at low temperature, high aspect ratio, well crystalline nanorods were observed. X-ray diffraction and Infrared spectroscopy suggests that the nanorods correspond to lepidocrocite (γ-FeOOH). TEM analysis shows each bundle consisting of several nanorods stacked together by side on fashion. γ-FeOOH nanorods with high aspect ratio of 70 were observed. The SQUID analysis reveals that the lepidocrocite nanorods exhibit superparamagnetic behavior at room temperature.