Abstract: A method of obtaining nanoparticles of gadolinium oxide by the sol-gel method from a gadolinium nitrate solution is considered. The conditions of gadolinium oxide precipitation and the size of colloidal particles are determined. Using differential scanning calorimetry (DSC), the phase transitions of gadolinium hydroxide gel on cooling to a negative temperature followed by heating from –30 to 250°C and mass loss (88.4%) in the gel during the heating to 250°C are established. The dependence of the degree of conversion in the dehydration process on the temperature is found and the activation energy of this process is calculated (54.03 kJ/mol). The particle size after the gel calcination (8–16 nm) is estimated using the TEM method.