Chilli powder samples were irradiated by a ⁶⁰Co gamma source at absorbed doses of 2, 4, 6 and 8 kGy. This study calculates the activation energy value (E) from the thermoluminescence (TL) glow curves using the initial rise method (IR). For non-irradiated samples, the E value is 0.58 eV, whereas the irradiated samples have a higher value of 0.84 eV. This difference allows us to distinguish between irradiated and non-irradiated chilli powder and to assess the dose of gamma-irradiated samples.