Superparamagnetic Fe3O4 nanoparticles with diameter of similar to 7 nm were prepared by a colloidal method, without employing surfactants and using precursors like FeCl3 center dot 6H(2)O, FeSO4 center dot 7H(2)O, deionized water and using NH4OH solution (29% vol.) as precipitating agent. The synthesized product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy attached with energy dispersive X-ray (SEM-EDS), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area, thermogravimetric analysis (TGA-DTG), and atomic force microscopy (AFM). The hysteresis loops of the magnetite nanoparticles were measured using a superconducting quantum interference device (SQUID) and the results showed a superparamagnetic behavior at room temperature.