The synthesis and characterization of a series of N-heterocyclic carbene (NHC) complexes of Au(iii), (NHC)AuCl3, is described. High yields are obtained when the corresponding Au(i) species (NHC)AuCl are oxidized with inexpensive aqua regia. The oxidation is in some cases accompanied by substitution and/or anti addition of Cl2 across the backbone C[double bond, length as m-dash]C bond of unsaturated NHC ligands.