Electron paramagnetic resonance (EPR) can be used as radiation detection for appropriate materials exposed to ionizing radiation. In this study, potassium tartrate hemihydrate (PT) was irradiated with Co-60 gamma rays with absorbed dose range from 1 to 9 Gy. The effect of temperature to the unirradiated and irradiated samples were investigated using electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra were recorded in the temperature range from room temperature (293 K) to 413 K. The results show that the unirradiated PT sample does not exhibit any EPR signal when thermal energy is given to the sample. However, the irradiated PT samples exhibit EPR spectrum with three lines recorded at room and high temperatures. The main strong line dominates the spectrum of the irradiated PT sample appears at g = 2.0032. Heating the irradiated sample above room temperature showed increases in signal intensity. The dose response curves of the signal at variable temperature were described well by a linear function