The electrochemical behavior of a series of five cationic species containing the Au(bipy)(3+) moiety and additional oxygen-donor ligands, and of the relevant common precursor, i.e. the dichloride [Au(bipy)Cl-2][PF6] species, have been investigated using cyclic voltammetry and controlled-potential coulometry. All the compounds with oxygen-containing ligand(s) (2-6) undergo an easy, irreversible one-electron reduction process. The first reduction process of the dichloride consists of an equally easy but quasi-reversible charge transfer, as evidenced by voltammetric tests at a very high scan rate, followed by an irreversible second-order chemical reaction. Correlations between the relative values of the reduction potentials and the corresponding molecular structure are made and hypotheses on the nature of the reduction mechanisms are advanced. (C) 2000 Elsevier Science B.V. All rights reserved.