Plasma polymerization using a direct current (d.c.) glow discharge was carried out using several organic compounds. We have developed a plasma-polymerization instrument capable of using not only gaseous monomers but also liquids and solids as the starting materials. The characteristics of films prepared by d.c. glow discharge were examined by Fourier transform infrared spectroscopy and Raman spectroscopies, electron spectroscopy for chemical analysis, and contact angle measurements. The chemical structures of the deposited films were greatly influenced by the applied d.c. voltages during the discharge. Hydrogen-fret carbon films were prepared from plasma polymerization of both naphthalene and benzene; the structure of these films, evaluated by Raman spectra, were quite different. Comparison of films deposited in different regions of the plasma, such as in the negative glow-phase region and in the positive column region, were performed. From these experiments similar film compositions were obtained.