Thin solid films were prepared by the plasma polymerization of quinoline in order to obtain polymeric films with a highly conjugated pi electron system. The electronic structure of these plasma polymers was characterized in situ by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) and by ex situ Fourier transform infrared (FTIR) spectroscopy. The films were doped by iodine and the doping mechanism was analysed by UV-visible and FTIR spectroscopy and electrical resistance measurements. A comparison of the electronic structure and electrical properties of these plasma polymers with those of plasma polymers of pyridine and benzene was performed.