There have been considerable developments in the field of hard cartxm thin film deposition in the past decade. The films show properties of extreme hardness, chemical inertness and optical transparency and their use has been suggested for wear protective coatings. The results presented here concern the use of Plasma Enhanced Chemical Vapour Deposition (PECVD) to produce these films Details of the effects of the important deposition parameters on their mechanical properties are presented. The deposition system design and implementation are desenbed. The resultant film charactenstics are presented graphically as a function of the deposition vanables Films were produced which exhibited extreme hardness of up to 3000 Vickers. Their deposition rate was found to decrease with substrate temperature and increase with induced bias and pressure. The intrinsic stress and wear resistance were found to increase with the induced bias and substrate temperature but decreased as the pressure was increased. The film adhesion was found to improve at higher temperature and bias and also at higher pressure but films in this region were found to be of reduced hardness. The intrinsic stress and poor adhesion of carbon films were identified as the main difficulties in the application of these films as wear protective coatings Possible ways of improving these film charactenstics were investigated. The main deposition vanables of substrate temperature, induced bias and pressure were identified, along with the possible optimisation of carbon thin film charactenstics by control of the deposition environment.