Properties of diamondlike coatings deposited in a modified design of the plasma reactor system are reported. Benzene and monosubstituted benzenes are used as the source gases. The films have been analyzed using scanning electron microscopy, glancing angle x‐ray diffraction, Fourier transform infrared spectroscopy, and x‐ray photoelectron spectroscopy techniques. Large crystallites (∼30 &mgr;m) are observed. The x‐ray diffraction and x‐ray photoelectron spectroscopy have been utilized to identify the physicochemical nature of the deposited films. Fourier transform infrared spectroscopy results suggestsp3type of bonding in the films. Films are colorless, electrically insulating (≥109&OHgr; cm), and corrosion resistant.