Cyclic voltammetry has been employed to study the diffusive, irreversible platinum(II) → platinum(0) reduction of three sets of structurally related complexes: cis-[PtCl 2P{ p-C 6H 4X} 3) 2] (X = H, CH 3, Cl, F, OCH 3, N(CH 3) 2); cis-[PtCl 2(PPh 2R) 2] (R = CH 3, n-C 3H 7, n-C 5H 11, n-C 6H 13, n-C 12H 25) and cis-[PtCl 2(PR 3) 2] (R = CH 3, C 2H 5, CH 2ch 2CN). Relationships between the peak potentials for the Pt(II) → Pt(0) reduction and thermodynamic parameters which measure the electronic properties of the ligands are shown to exist for complexes of P{ p-C 6H 4X} 3 ligands, implying a thermodynamic origin for the sensitivity of the peak potentials to structural change. Complexes of both P{ p-C 6H 4X} 3 and PPh 2R ligands show correlations between peak potentials for reduction and the 31P{ 1H} NMR spectroscopic parameter, 1J( 195Pt, 31P). Correlations with values of δ( 31P) exist in both cases, but a correlation with the coordination chemical shift, Δδ( 31P), exists for complexes of PPh 2R, and not for complexes of P{C 6H 4X} 3. Complexes of PR 3 ligands show no correlation between the peak potentials measured for the Pt(II) → Pt(0) reduction and electronic or spectroscopic parameters, except possibly 1J( 195Pt, 31P).