A study on the characterization of the electrical conduction behaviors of semi-transparent patterned polypyrrole thin films fabricated on glass slides by soft lithography and in situ deposition is described in this paper. The SEM (Scanning Electron Microscopy) voltage contrast test on these thin films shows that the polypyrrole deposited on the micro-contact-printed glass surfaces terminated with hydrophobic octadecylsiloxane is conductive while that deposited on the non-printed hydrophilic glass surfaces is not conductive. The SEM morphology study shows that the morphology of polypyrrole deposited on the micro-contact-printed glass surface is completely different from that on the non-ptinted glass surface. Further SEM morphology analysis on the polypyrrole deposited near the edge of the micro-contact-printed area on the glass surface shows that a sharp boundary appears between these two completely different morphologies of deposited polypyrrole, which results in highly conductive polypyrrole with well-defined micro-contact-printed patterns embedded in poorly conductive polypyrrole. These patterned polypyrrole thin films are suitable for use as electrodes in optical devices, such as "light valves" based on polymer dispersed liquid crystal composites or other inexpensive semi-micron electronic circuitry. (c) 2007 Elsevier B.V. All rights reserved.