Annotation The European Federation of Corrosion's Working Party on Surface Science and the Mechanisms of Corrosion and Protection (EFC WP6) has defined, as one of its objectives, the development of a reference material and reference guidelines for the application of electrochemical scanning tunnelling microscopy (EC-STM) in corrosion science. The use of EC-STM to study the relationship between surface structure and surface reactivity in situ on electrodes in contact with an electrolyte is of major importance in corrosion research. This report describes the reference material and procedural guidelines required to use this technique effectively. STM-users are instructed how to obtain high resolution data on a carefully prepared copper single-crystal surface.