A ceramic composite containing the high-temperature superconductor YBa2Cu3O7-x and alumina has ideal characteristics for absorbing energy from radio-frequency (r.f.) electromagnetic fields at high temperatures. It is an effective catalyst for the oxidation of methane in a cyclic mode of operation in which methane and air are fed consecutively to the reactor. Lattice oxygen is alternatively consumed to form CO(x) and water and then regenerated. This facile movement of oxygen anions was monitored by following the cyclic changes in electrical conductivity. In a conventional tubular reactor at 1000 K, the products are largely those of total oxidation. In contrast, preliminary work in an r.f. reactor showed evidence of some production of C2s from the methane coupling reaction.