At the Institute of Electrochemistry electrochemical reactions on single-crystal surfaces in contact with a (mostly) aqueous electrolyte are investigated. In this the influence of the surface structure on the reactivity of electrodes plays a special role. Thus, in close combination of experiment and theory, fundamental issues of electrochemical systems and boundary layers often directly related to different applications, e.g. from the fields of energy storage and conversion, electromobility or metal deposition, are processed.