Intrinsically conductive plasma polymers were formed in a 2.45 GHz microwave low pressure plasma. The electrical conductivity and structure of the polymeric films were compared with those of electrochemically polymerized polythiophene. A new method of doping was tested using the iodine-containing monomer 2-iodothiopene. Films with high electrical conductivity (10-1 down to 10-6 S cm-1) could be produced, and their chemical structure was studied by X-ray photoelectron spectroscopy and Fourier transform IR spectroscopy. The IR spectra give a strong indication that the chemical structure of these films is comparable with that of electrochemically deposited polythiophene. Optical emission spectroscopy was used to give in-situ information about the fragmentation mechanism in the plasma.