The electrode kinetics for the one electron reduction of bis(biphenyl)chromium(I) tetraphenylborate were studied in N,N-dimethylformamide as a function of the concentrations of the supporting electrolyte tetrabutylammonium perchlorate. Cyclic voltammetry on a hemispherical mercury ultramicroelectrode as well as a.c. polarography on the dropping mercury electrode were employed to obtain k(s)(app) and a values. An increase in the standard electrode reaction rate constants with increasing concentrations of the supporting electrolyte was observed. Measurements in other supporting electrolytes (sodium perchlorate, tetrabutylammonium hexafluorophosphate and tetrabutylammonium tetraphenylborate) showed only minor influences of the nature of the supporting electrolyte on the kinetics of the electroreduction of bis(biphenyl)chromium(I). The observed changes in the apparent reaction rate constants are discussed, together with the influence of the solvents and electrolytes on the kinetic behaviour of other organometallic redox systems.