In the last decade the magnetic nanomaterials based on iron oxides are intensely studied due to the possibility of their use in different fields as: magnetic storage media; biosensor application; contrast agents in NMR imagine; medical application; magnetic inks [1]. Some well known methods to obtain iron oxides nanoparticle are: electrochemical synthesis; reduction of metal salts in the presence of suitable (monomeric or polymeric) stabilizers; decomposition of organometallic precursors; vapor deposition methods [2]. In the Laboratory of Bioinorganic Chemistry and nanocomposites of the Institute of Chemistry of Academy of Sciences of Moldova the method based on thermal decomposition of µ-oxo iron carboxyclusters is used. In the present work, the mixed valence iron acetate was taken as the precursor in the process of obtaining iron oxides nanoparticles (T= 310 oC, oleic and thrichloroacetic acid, and dodecylamine. The obtained product was studied with the Mossbauer Spectroscopy (MS) at different temperatures: 298, 80, 40, 20, 15, 6,5 K. The form of spectra is represented as doublet (T > 80 K) or doublet and two sextets (T<60 K) as is shown in figure. The MS parameters of doublet are characteristic for the Fe(3+), S=5/2. With the temperature decrease, the intensity of the doublet significantly decrease, and intensity of the sextets increase. The variation of SM spectra can be interpreted in the limits of the effect of superparamagnetism (5-10 nm). The block temperature (Tb) of the inside magnetic field reorientation is situated in the limits of 80-40 K. The presence of the doublet at 6,5 K suggests that the obtained product also contains particles smaller then 5-10 nm (confirmed by TEM), which represents about 12 % of the sample. The sextets were assigned to the amorphous phases of γ-Fe2O3 and Fe3O4 (confirmed by powder XRD).