The electrochemical behaviour of the series of ten [Rh(RCOCHCOR')(P(OPh)(3))(2)] complexes with R, R' = CF3, CF3 (1), CF3, Ph (C6H5) (2), CF3, CH3 (3), Ph, Ph (4), CF3, Fc (ferrocenyl = (eta(5)-C5H5)Fe(eta(5)-C5H4)) (5), CH3, Ph (6), CH3, CH3 (7), Fc, CH3 (8), Fc, Ph (9) and Fc, Fc (10) by means of cyclic voltammetry in CH3CN shows Rh(I) being oxidized in an electrochemically irreversible two-electron transfer process at a lower oxidation potential than Fe. Relationships between the electrochemical oxidation potential of rhodium (E-pa) and experimental oxidation potential (as measured by the second order oxidative addition rate constant K-2), density functional theory calculated charges and energies (Sigma Q(Mulliken), Sigma Q(Hirshfeld), Sigma Q(MDC), Sigma Q(Bader), Sigma Q(NPA), ionization potential and E-HOMO) and electronic parameters of the beta-diketonato ligand RCOCHCOR' (electronegativities (chi(R) + chi(R')), PKa, Hammett meta substituent constants (sigma(R) + sigma(R')) and Lever electronic parameter E-L) of [Rh( beta-diketonato)(P(OPh)(3))(2)] complexes 1-10, show that E-pa can be predicted with a high degree of accuracy for related [Rh(beta-diketonato)(P(OPh)(3))(2)] complexes. (C) 2013 Elsevier Ltd. All rights reserved.