This work presents a systematic study on a commercial high electron mobility transistor based on the AlGaN / GaN heterostructure (GaN HEMT). The study evaluates its robustness to different radiation doses, more specifically, its robustness to the effects of the total ionizing dose (TID) irradiated from an X-ray source with an effective energy of 10 keV. The accumulated dose varies from up to 350 krad (Si). Therefore, for this purpose, three tests were performed on the commercial transistor, GS61008T. First, the acquisition of parameters: threshold voltage (VTH), Transconductance (gm), off current (Ioff) and sub-threshold slope (S) before, during and after exposure to radiation. Then, the switching test, where the rise (tr) and fall (tf) times were aquired, pre and post irradiation, in two diffrent frequency, 100 Hz and 100 kHz. Moreover, the temperature test, where the sample varied from 223 K (-50ºC) to 348 K (75 ºC) to evaluate its robustness for the temperature variation after having accumulated 350 krad (Si). In addition, for a better understanding of the effects of TID on the sample, all tests were performed in two different polarization modes. The on mode (VGS = 3 V and VDS = 0 V), and the off mode (VGS = VDS = 0 V). The characteristic electrical parameters of the transistor were extracted using the characteristic curves IDxVD, IDxVG and IDxt. Curves, that were obtained using National Instrument’s PXI, with programmable sources and an X-ray diffractometer. The results showed that for the devices analyzed, for this GaN COTS the effects resulting from ionizing radiation (TID), with doses up to 350 krad (Si), are minimal, and also showed a quick and effective recovery of their electrical characteristics after annealing at room temperature, especially when irradiated polarized at on mode. Therefore, indicating that they are good candidates for use in harsh environments, as is the case of aerospace environments, particle accelerators environments and nuclear reactors