The effect of applied current on the morphology, particle size, structure, and magnetic properties of magnetite nanoparticles prepared by electro-crystallization method was studied. The synthesis was performed in an electrochemical cell containing two iron electrodes and an aqueous solution of sodium sulfate, and either thiourea, sodium butanoate, or beta-cyclodextrine as organic stabilizer. All the samples were characterized by XRD, SEM, VSM, and Mossbauer spectroscopy. X-ray diffraction patterns, clearly confirmed that all products have the cubic spinel Fe3O4 crystal structure. Electron microscope images of the samples showed that their mean particle size is in the range 20-80 nm, and depends critically on the applied current and type of the organic additives. Specific magnetization of the samples at room temperature ranges from 60 to 90 A m(2) kg(-1), depending on the growth conditions. Room temperature Mossbauer spectra are typical of nonstoichiometric Fe3-delta O4, with a small excess of Fe3+, 0.06 <= delta <= 0.17. (C) 2015 Elsevier Ltd. All rights reserved.