Radiation dosimetry was undertaken using an electron spin resonance (ESR) spectrometer in students' laboratory work. Sugar was used as a dosimeter element and irradiated with both an X-ray generator (34 kVp, 8 mA) and a 60Co sealed source (3.7 MBq). The ESR system detects unpaired electrons created by the ionizing radiation. The lowest detection limit of the absorption dose was 20 Gy.