[en] NaCl:Ca phosphor is investigated as a material for thermoluminescent dosimetry in the temperature range 300deg -500deg K. The glow curves show two main peaks at 350deg and 470deg K even for different durations of X-irradiation. This indicates that the duration of X-irradiation does not affect the luminescent centres, trapping centres and the base material. The intensity of 470deg K glow peak is linearly dependent on the incident energy. The phosphor, therefore, satisfies the requirements of high TL-efficiency and resistance to radiation damage. Its main disadvantage is atmospheric contamination which can be prevented by shielding the phosphor from direct exposure to contaminating agents. (M.G.B.)