The reduction and adsorption capacities of hierarchically structured carbon films synthesized from glucose on a molten magnesium catalyst under a layer of molten salts and thermally reduced graphene oxide are studied during their interaction with a sodium permanganate solution in a neutral medium at room temperature. The X-ray photoelectron spectroscopy data show that all manganese adsorbed on the surface of the carbon nanomaterials exists in a reduced form: the major part exists in the form of tetravalent manganese, and about 20% exist as trivalent manganese ions. Therefore, the synthesized carbon–oxide composites are considered to be promising materials as cathodes in chemical current sources. Thermally reduced graphene oxide demonstrates the lowest adsorption activity. The hierarchically structured carbon films make it possible to adsorb up to 100 wt % initial manganese in neutral media, which is much higher compared to all well-known commercial adsorbents.