Planar cells incorporating a microelectrode as the working electrode were prepared using materials and techniques commonly employed in fabrication of planar solid oxide fuel cells. Initial results of ac and dc polarization measurements suggest that these cells potentially offer excellent isolation of working electrode frequency response (impedance), and quantification of steady-state current-overpotential relationships. The success of the technique relies heavily on how precisely the geometry of the microelectrode pattern is defined and characterized. Some of the challenges in implementing this technique are discussed. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.1945729] All rights reserved.