The mechanism of an elementary act is undoubtedly one of the most fundamental problems of chemical and, in particular, electro- chemical kinetics. Although this problem has fascinated scientists for quite a long time, it was only in the late fifties and early sixties that it began to be actively investigated for charge transfer reactions. Owing to the development of new methods in the analysis of this problem, significant advancements were made in theoretical as well as experimental studies. These investigations showed that the physical mechanism of charge transfer in all processes including...