A direct-current plasma enhanced chemical vapour deposition (PECVD) system was designed and built in-house for the deposition of hydrogenated amorphous carbon(a-C:H) thin films. In this work, a-C:H thin films prepared using this system at different deposition pressures were studied. The influence of deposition pressure on the deposition rate, energy gap, bonded hydrogen content and structure of the film has been investigated. The characterization techniques were determined from optical transmission spectroscopy, Fourier transform infrared spectroscopy and Xray diffraction measurements. The results demonstrated that the deposition pressure had strong influence on the deposition rate, optical energy gap and the bonded H content in the film. Evidence of crystallinity was observed in films prepared at low deposition pressure.