In this work, we have investigated the thermal stability of the organic component of porous SiO2 (xerogel) films using a combination of ion beam techniques and thermal desorption spectroscopy (TDS). Ion beam techniques reveal a large concentration of carbon and hydrogen atoms in this film. The presence of these elements arises from the surface modification step in xerogel film processing, where the surface Si bonds are passivated by organic complexes in order to avoid moisture adsorption. These organic components of the film are shown to be stable under typical semiconductor processing temperatures of < 450 degreesC. However, at 600 degreesC, there is a significant reduction in hydrogen and carbon concentration that could lead to moisture adsorption. The combination of ion beam techniques and TDS is shown to be useful in characterizing the thermal stability of these films.