The influence of different inorganic additives including KCl, HAuCl4 center dot 3H(2)O, Dy(NO3)(3)center dot xH(2)O, and La (NO3)3 center dot 6H(2)O on structure and magnetization of magnetite nanoparticles was studied. The nanoparticles were synthesized by electrocrystallization of iron plate using a chronoamperometric technique in an aqueous medium. X-ray diffraction patterns confirmed the formation of inverse cubic spinel structure of magnetite. Based on XRD results the variations of additive concentrations can improve or strongly change the structure of the samples. Electron microscopy images showed the mean particle size varies from 14 to 70 nm depending on the additive concentration. Room-temperature magnetization ranges from 45 to 84 Am-2 kg(-1), related to the particle size and additive concentration. It is possible to improve the structure and magnetization of particles by adding potassium chloride in the electrochemical cell. Mossbauer data show that the samples are slightly nonstoichiometric Fe3-delta O4, with 0.01 <= delta <= 0.13. The paramagnetic doublet contribution highly changes in intensity with variation of additive and its concentration. (c) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.