Diamond-like carbon and carbon nitride films were deposited on high speed steel substrates by plasma enhanced chemical vapour deposition technique. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to investigate the different bondings. Adhesion of the films to the substrate was investigated by the scratch test technique. The mechanical properties were investigated by nano-indentation and the tribological behaviours were tested using a ball-on-disk tribometer. Effect of annealing on adhesion and mechanical properties was also investigated.