Mechanical and electrical properties of high molecular weight polyaniline/ multiwalled carbon nanotube composite films were investigated. Addition of carbon nanotubes to polyaniline films was accomplished by solution processing. Physical characterization of these composites by thermogravimetric analysis, tensile testing, dynamic thermal mechanical analysis, and atomic force microscopy measurements indicate that polyaniline containing 1% carbon nanotubes is more mechanically and thermally stable than neat polyaniline. Rectifying aluminum contacts were fabricated using this composition of the composite material, along with neat polyaniline for comparison. The measured electrical characteristics indicate that the current levels of the polyaniline/ carbon nanotube composite devices are nearly an order of magnitude higher than those of the polyaniline devices; thus, this composite material has the potential for applications in organic electronics. (C) 2004 The Electrochemical Society.