The kinetics of the intra-molecular electron transfer of the adduct of l-ascorbic acid and a series of mixed metal Cr 2 Fe oxo-centred trinulear complexes, of the general formula [Cr 2 Fe(μ 3 -O)(μ 2 -RCO 2 ) 6 (H 2 O) 3 ] + (where R=H, CH 3 , CH 3 CH 2 and (CH 3 ) 2 CH) were investigated spectrophotometrically, in aqueous carboxylate buffer. The reactions were studied over the ranges 2.34⩽pH⩽4.45, 25.0⩽θ⩽35.0°C at an ionic strength of 0.50moldm −3 (NaClO 4 ). The reaction involves an equilibrium step between both triaqua and diaquahydroxo species of the complex cations and l-ascorbic acid, resulting in the formation of an adduct. These equilibrium steps are followed by a slower one-electron oxidation step, corresponding to the reduction of the iron(III) centre(s) which is proceeded by rapid decomposition of the oxo-centred trinuclear core to yield aqueous iron(II), and dinuclear chromium(III). The dinuclear chromium(III) further decomposes by aquation to give an aqueous solution of the metal ions and free ligands.