AbstractThe relatively long lived ascorbic acid radical or the ferrihexacyanide anion were produced by a 20 ns pulse of high energy electrons in N2O saturated, 10−3molar solutions of ascorbic acid or ferrohexacyanide anion, respectively. Their cathodic currents at a hanging mercury drop electrode were recorded as function of time in the micro to millisecond range. The analysis of current‐time curves at constant potential was carried out in the same way as in the single potential jump experiments of conventional electrochemistry. Absolute values of the rate constant of the transfer processes could be obtained for various potentials. The transfer coefficient was found to be 0.23 for the ascorbic acid radical and 0.15 for the ferrihexacyanide anion. The exchange current density at the standard potential of the system [Fe(CN)6]3‐[Fe(CN)6]4‐was calculated as 3.5 mA · cm−2at a concentratio