Electrochemical techniques using microcapillaries as electrochemical cells allow to study local processes on metal surfaces. Since the usual large-scale electrochemical techniques provide only average data integrating over a large surface area (mm2–cm2), they are inadequate to investigate local corrosion processes. Due to the enhanced current resolution of the microelectrochemical methods down to pA and fA, processes in the micro- and nanometer range can easily be studied. This method allows to perform local electrochemical investigations of single areas of special interest, such as grain boundaries, second-phase precipitates or inclusions. Therefore, the microcapillary technique is well suited to study the corrosion behavior of microsystems. Results obtained from studies of localized corrosion processes of stainless steels are presented and discussed.