A new phosphor KCaSO4Cl is very interesting for thermoluminescent properties. In this article, we present results concerning the main dosimetric properties of KCaSO4Cl activated by Ce, Dy, Mn, and Pb at various concentrations. Polycrystalline KCaSO4Cl: (Ce; Dy; Ce, Dy; Mn; Ce, Mn; Pb and Ce, Pb) phosphors prepared by solid state diffusion method have been studied for its thermoluminescence (TL) characteristics. The TL glow curves of gamma-irradiated all KCaSO4Cl samples show strong single glow peaks indicating that only one type of trap can be formed. The intensity of the TL glow peaks increases with increase of the gamma-ray dose to the samples but the intensity of the TL glow peaks increases with decrease of the concentration of the dopent. The sensitivity of all the phosphors presented here are more than that of CaSO4: Dy. The phosphors have a simple TL glow curve structure with a prominent peak at the lower temperature side. TL response, fading, reusability of the phosphors are also studied, and it is found that the phosphor is quite suitable for use in dosimetry of ionizing radiations.