Many technically relevant materials are non-homogeneous in structure. Their investigation requires a locally resolved surface analysis. An exact determination of the accessed area and a potentiostatic control in a three-electrode configuration are necessary. This becomes possible by capillary-based microcells which enable local impedance measurements and even impedance mapping of the surface. Different aspects and strategies of this microimpedance spectroscopy are presented and discussed, together with some examples. (c) 2005 Elsevier Ltd. All rights reserved.