Adhesive polythiophene films were formed in a new two‐step procedure using 11‐(3‐thienyl)undecyltrichlorosilane as a surface coupling agent and a chemical polymerization for reinforcing the film. Coating experiments were carried out on several substrates which are interesting for many kinds of applications. Adherent junctions were available, for instance, on etched silicon and , , polished aluminum, and quartz substrates for piezoelectric elements. Polymer films on silicon surfaces were characterized by ellipsometry, scanning electron microscopy, atomic force microscopy, X‐ray photoelectron spectroscopy, and Raman microscopy. © 1999 The Electrochemical Society. All rights reserved.