Publisher Summary This chapter discusses the contribution that can be made by dynamic electrochemical methods toward the often-difficult task of defining reactions of Fe–S clusters in a protein molecule. Despite the relatively modest amount of material published to date, these reports show that such an approach, when combined with appropriate spectroscopic techniques, can yield valuable insight. The adsorbed film studies of Dimorphognathus africanus Fd III described in the chapter illustrate a new strategy for studying proteins with very reactive Fe–S clusters. The approach combines high sensitivity, accuracy, and the ability to study reactions under strict conditions of applied potential. Equilibrium and kinetic data may be derived with trace amounts of protein, and verified by the preparation of appropriate spectroscopic samples. From the results of spectroscopic studies on the products of parallel transformations carried out in solution, it is demonstrated in the chapter that the voltammetric interrogation of Fe–S proteins in an adsorbed film can provide an acceptably valid reflection of the chemistry of free molecules. A useful trailblazing capability is thus provided to give guidance and to complement the techniques aimed at detailed structural characterization.