This paper provides a brief review of a relatively new technique, namely scanning electrochemical microscopy (SECM), and its applications in measuring, characterising and evaluating corroding systems. Localized corrosion processes and electrochemical activity distributions in surfaces can thus be investigated in real time with high spatial resolution. The SECM is a unique near-field scanning technique that is electrochemically integrated as to detect chemical and electrochemical activities in electrochemical heterogeneous systems such as those operating in corrosion research. The SECM can be used in a variety of ways, which can be broadly classified into amperometric and potentiometric modes, depending on the type of the sensing probe, namely an ultramicroelectrode (UME) and an ion-selective microelectrode, respectively. The operation modes of the instrument are described together with typical experiments selected to illustrate their application in sensing localised corrosion.
