inorganic-polymer composites are widely used as radio-absorbing materials, the study of their properties is important from the point of view of improving technical characteristics. The results of the study of Nafion/thermoexpanded graphite and Nafion/carbon black composites by nuclear magnetic resonance and thermogravimetry are presented. The formation of new compounds at the contact boundaries of the components, leading to thermal stabilization of the composites, is shown. Differences between thermally expanded graphite and carbon black upon interaction with Nafion are discussed.