[en] Magnetite nanoparticles were synthesized by two methods: reverse coprecipitation and partial oxidation of ferrous ions. The particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, vibrating sample magnetometry (VSM), and thermogravimetric analysis (TGA). The prepared nanoparticles exhibited superparamagnetic properties at room temperature. The mean size of the particles was in the range of 10-29 nm. TGA curves showed different thermal decomposition behaviors depending on the synthesis method. Distinct magnetic responsiveness was observed for the TGA residue samples. Thermal decomposition kinetics was evaluated by the model-based approach using TGA curves measured at three distinct heating rates in the temperature range of 298-1173 K under a synthetic air atmosphere. The model fit resulted in a correlation coefficient of 0.998 and the order of magnitude for the estimated kinetic parameters agreed with the reported data in the literature. (author)