AbstractThis review deals with the literature (covered up to August 1983), the characterization and the applications of Surface‐Modified Electrodes (SME). As a special class of SME's, the Enzyme‐Modified Electrode (EME) is introduced.Three types of modification procedures are distinguished;i.e.covalent modification, adsorption modification and polymer‐film modification. A further subdivision is made for catalysts attached to the electrode surface directly or via a bridge molecule. The characterization of SME's is mainly achieved via electrochemical techniques such as cyclic‐ and ac‐voltammetry. This theory is briefly described and illustrated with some of our own results.The name EME is used for a system in which the enzyme is immobilized at the electrode surface, such that direct electron transfer between electrode and enzyme becomes possible.The last part of this review deals with the applications of SME's and EME's. Examples are given of some already realized and of some possible app