The thermal decomposition of μ3-oxo trinuclear iron(iii) acetate in presence of dodecylamine and oleic acid, in trichloroacetic acid at 320 °C was optimized to obtain iron oxide nanoparticles with pure nanowire morphology. The amount of oleic acid having a surfactant role, beside the ligand exchange for acetate, was used as a control parameter. The size and morphology of the resulted particles were evaluated on the basis of transmission electron microscopy images. Thermal stability and the content of the organic component of the naoparticles were determined by thermogravimetrical analysis. The ordering degree of the organic and inorganic phases constituting the nanoparticles was investigated by wide angle X-ray diffraction, small angle X-ray scattering and polarized optical microscopy. Superparamagnetic state was verified by Mössbauer spectroscopy and the magnetic behavior was studied by SQUID magnetometry. The preservation of the morphology of the particles after complete thermal decomposition was verified by transmission electron microscopy.