The incorporation of fluorine in hydrogenated silicon carbide films was carried out by pulsed glow discharge deposition, and its effects on the structure, mechanical, optical, and surface properties were investigated. Fluorine incorporation occurs mostly in the form of single Si-F bonds and no C-F bonds were revealed by infrared and x-ray photoelectron spectroscopies. Films with higher F contents have lower Si/C ratios, and the excess of C favors the formation of graphitic agglomerates which decrease the hardness of the films. Films with 16 at. % F exhibit 10 GPa hardness. Our results indicate that the chemical states in which F is incorporated into a-SiC:H films play important roles in the surface and optical properties. C-F bonds, in opposition to Si-F bonds, control the wettability and optical gap of this material. (C) 2004 American Vacuum Society.