This study investigates the thermoluminescence (TL) properties of natural obsidian samples collected from the Aksaray region in Turkey. The obsidian samples were ground into powder and sieved into five particle size ranges between 63 and 500 μm. The grain size range of 63–125 μm was identified as the most suitable for TL measurements, as it produced a sharper and more intense peak in the dosimetric region of the spectrum. Subsequently, detailed analyses were conducted on the TL glow curves, reusability, dose response, and heating rate behavior of the selected sample. The effect of heating rate was tested over a range of 0.1°C–10°C/s, revealing an anomalous heating rate dependence. Kinetic analysis using the (Formula presented.) method identified multiple peaks, indicating the presence of various energy levels. TL curve deconvolution using the general order kinetics model yielded activation energies ranging from 0.82 to 1.68 eV and demonstrated a strong correlation between the experimental data and theoretical predictions.