Remarkably, disclosed herein is a solvent-less chemical vapor deposition (CVD) method for the oxidative polymerization and deposition of thin films of electrically-conducting polymers. In a preferred embodiment, the method provides poly-3,4-ethylenedioxythiophene (PEDOT) thin films. In other embodiments, the method is applicable to polymerization to give other conducting polymers, such as polyanilines, polypyrroles, polythiophenes and their derivatives. The all-vapor technique uses a moderate substrate temperature, making it compatible with a range of materials, including as fabric and paper. In addition, this method allows for the coating of high surface-area substrates with fibrous, porous and/or particulate morphologies. The coated substrates may be used in organic semiconductor devices, including organic light-emitting diodes (OLEDs), photovoltaics, electrochromics, and supercapacitors.