In the current work, we investigated the Thermogravimetric kinetics of degradation of high-density polyethylene (HDPE) alone, and mixed with silicoaluminophosphate catalyst (SAPO-37/HDPE). To estimate the kinetic parameters of the polymer degradation, the Vyazovkin model-free kinetic method was applied. The activation energy (E) was calculated as a function of conversion (alpha) and temperature (T), providing an estimate of the time required for the degradation process at a given temperature. The products due to thermal and catalytic cracking of polyethylene were analyzed by gas chromatography/mass spectrometry (GUMS). The SAPO-37 showed good catalytic activity, decreasing the activation energy for the process.