Presented are the results of a systematic study of the effects of reactor pressure and rf power level on the electrical and chemical characteristics ofa‐C:H films prepared by glow discharge. Electrical resistivity has been found to increase rapidly with decreasing reactor pressure. This increase in electrical resistivity corresponded to an increase in thesp3bonding content of the film. This composition change has been attributed to increased ion bombardment energy and greater time for adatom surface migration. Electrical resistivity decreased with rf power level. Thesp2bonding content of the film decreased while thesp3bonding content increased with rf power level. The resistivity change and corresponding composition change could not be explained with the present model.