<p>Currently, most studies on hydrophobic silica xerogels focus on enhancing their application properties, such as thermal insulation and hydrophobicity, while relatively few investigations have addressed their pyrolysis mechanisms and products. In this study, we calculated the activation energies for the pyrolysis of homemade hydrophobic silica xerogels in air and helium atmospheres using multiple modeless function methods. We also determined the reaction mechanism functions of the samples in these two atmospheres through the master plot method. Additionally, we used various characterization techniques to compare the changes in the samples before and after heat treatment at 800&#xa0;°C in both atmospheres. Finally, the gas products generated during pyrolysis were detected and analyzed using a TG-IR-MS coupling technique. The results indicate that high-temperature conditions not only degrade the structural integrity and application properties of hydrophobic silica xerogels but also result in the release of toxic and harmful gases under both aerobic and anaerobic conditions. Particularly in air, the presence of oxygen leads to a more complex reaction mechanism during the pyrolysis of hydrophobic silica xerogels.</p>