Electrochemical machining (ECM) becomes more important with increasing requirements on material properties, manufacturing technologies and workpiece quality. In the ECM community, microprocessing plays an increasing role in addition to conventional fields of ECM applications, i.e. aircraft manufacturing or the automotive industry. Besides regular metals, customers focus more and more on materials difficult to machine, such as cemented carbides, titanium or metallic glasses. For that reason, extensive knowledge of the fundamental electrochemical processes at high current densities is just as essential as the interaction between processing and material properties, and a further development of the technical equipment.