Propane deep oxidation, as a model reaction, was investigated to illuminate the intrinsic electrochemical promotion of catalysis (EPOC) by a nanodispersed Pt/yttria-stabilized zirconia catalyst powder. The thermally induced back-spillover of O2- ions from the ionic ceramic support to the Pt particle's surface was observed and confirmed to play a key role in enhancing the catalytic activity as an effective promoter. These results demonstrate that EPOC can be thermally induced without any electrical polarization by using nanoparticles of metallic catalysts supported on ionically conducting ceramics, which can be widely utilized as attractive alternative supports in various heterogeneous catalyses.