Various Pd-carbene complexes with bis(heterocyclic carbene) ligands were prepared and was investigated their catalytic activity for oxidative carbonylation of phenol with carbon monoxide to diphenyl carbonate (DPC). The catalyst system was composed of Pd complex, inorganic redox cocatalyst, organic redox cocatalyst, organic salt, and molecular sieve. The Pd-carbene complex systems PdBr2(c1-'Bu)/Ce(TMHD)(4) (TMHD: 2,2,6,6-tetramethyl-3,5-heptanedionate)/"Bu4NBr/hydroquinone showed approximately a double activity compared to a conventional PdBr2 catalytic system without the use of ligands. (C) 2003 Elsevier Science B.V. All rights reserved.