<p>This article investigates the thermal kinetics, degradation behavior, and lifetime prediction of Se_78-xTe₂₀Sn₂In_x (0 ≤ x ≤ 6) chalcogenide alloys using thermogravimetric analysis (TGA) over a temperature range of 300 °C–600 °C. Kinetic parameters were extracted using isothermal methods, including the Matusita-Sakka, Augis-Bennett, and Kissinger methods. By applying model-fitting approaches, we calculate the degradation energy (<i>E</i>_<i>d</i>) using the maximum degradation temperature (<i>T</i>_<i>d</i>) extracted from the DTG plots. The degradation temperature shows a dependence consistent with the Lasocka relation. Iso-conversional methods were also employed, utilizing the model-free approaches. A newly discovered logistic decay function is introduced to model mass loss phenomena, enabling the extraction of kinetic parameters such as the decomposition rate constant (<i>λ</i>_<i>d</i>) and decomposition time (<i>t</i>_<i>d</i>). Compositions STSI-1 and STSI-3 exhibit prolonged lifetimes and thermal resilience, underscoring their potential for applications in non-volatile memory devices, photonic switches, and radiation shielding.</p>