Oxidative carbonylation of phenol to form diphenyl carbonate (DPC) was investigated in the multi-step electron transfer system containing homogeneous or heterogeneous palladium as the main component. Carbon-supported Pd catalyst showed a better DPC yield than the best homogeneous system with Pd(OAc)(2) for the same amount of palladium. For the supported palladium catalyst, the hydrophobicity of the supports appeared to be critical for high yields of DPC. The palladium remained in the metallic state and dissolution into the reaction solution was, if there was any, negligible. Effects of promoters in carbon-supported Pd catalyst system were also examined.