The effects of thermal treatments on the thermoluminescent (TL) signal of NaCl (ACS reagent) induced by gamma radiation were investigated. Samples of NaCl were thermally treated at 500, 800 and 1000 °C and characterized by X-Ray diffraction and scanning electron microscopy. After their exposure 0.1 to 150 Gy of gamma radiation from a gamma-ray source of 60Co, a TL curve for each temperature of treatment was obtained. We observed a different TL behavior on the irradiated samples as a function of the temperature applied during the thermal treatments. For the sample treated at 500 °C, three peaks centered at 102, 133 and 228 °C were observed. Samples treated at 800 and 1000 °C showed two main peaks at 128 and 220 °C and 136 and 219 °C, respectively; however, the highest TL intensity signal was observed for the sample at 800 °C. All samples showed a linear dependency of the integrated TL intensity from the signal emitted as function of the irradiation time. This is an important advantage because NaCl could be applied as a very low cost thermoluminescent dosimetric material. A comparison between the TL signal induced by gamma radiation in pure and Eu doped NaCl is also reported.