The temperature-jump method has been used to determine the rate constants for the reaction[graphic omitted] over a range of temperatures. At 20°C and at an ionic strength of 0.1 M, kf= 1.2×107 M–1 sec–1 and kr= 1.8×106 M–1 sec–1. The forward and reverse activation energies are 5.7 and 7.5 kcal/mole, respectively. In addition, the rate constant for the exchange reaction [graphic omitted]was determined; k= 2.3×105 M–1 sec–1 at 25°C and at an ionic strength of 0.1 M. The net reaction was studied in the presence of so-called inert electrolytes such as LiNO3, KNO3, NH4Cl and N(CH3)4Cl. These salts affected the relaxation time, cations being more effective than anions. The Marcus theory was applied to these reactions, the calculated rate constants agreeing with experiment.