AbstractIn recent years optical methods have been extensively applied to assist in the elucidation studies of electrochemically induced phenomena. The objectives of these studies have been: (i) the characterization of the surface and electronic states of conducting and semiconducting materials; (ii) the in situ detection, characterization and kinetic monitoring of electrolytically generated reactive intermediates or products: (iii) the determination of the amount of coverage of surface adsorbed molecules and ions and their adsorption sites; and (iv) the electronic structure and physical properties of these adsorbed states. Three principal optical techniques have been employed: normal transmission spectroscopy, internal reflection spectroscopy and specular reflectance or ellipsometry. The first two techniques require the electrode to be at least partially transparent to the optical radiation. With the attainment of high sensitivity to small changes in radiation made possible by modulation and signal averaging methods, it has been demonstrated that considerable detailed description can be made regarding electrochemically induced surface changes as well as reactive intermediates in electrode mechanisms. The present state‐of‐the‐art of spectroelectrochemistry is examined and reviewed in this paper.