Gadolinium oxide nanoparticles were synthesized by the electrophysical method of spark discharge. Their structural features and magnetic and magnetocaloric properties have been comparatively analyzed. According to X-ray diffraction analysis data, the synthesized Gd2O3 nanoparticles contain two crystallographic phases, cubic and monoclinic. The magnetic entropy change ΔS M is determined from the data of magnetic isotherm measurements by the Maxwell relationship. The maximal ΔS M at a magnetic field change amplitude of 2 T is approximately 17 J/(kg K) and observed at a temperature of 2.5 K.