Hydrogenated carbon and carbon nitride films were synthesized by closed field unbalanced magnetron sputtering (CFUBM). The deposition rate, structure and mechanical properties of these films were studied as a function of applied bias voltage and nitrogen partial pressure on substrate during deposition. The film structures were investigated in Raman spectroscopy and FESEM. The hardness and elastic modulus were evaluated by nano-indentation test. Hydrogenated carbon films deposited at a bias of -200 V exhibited a maximum hardness and a minimum electrical resistivity and hydrogenated carbon nitride films synthesized at a nitrogen partial pressure of 0.2 Pa showed minimum friction coefficient. (c) 2005 Elsevier B.V. All rights reserved.