The hydrogenated amorphous carbon films doped with Ti and Si ((Ti,Si)–C:H) were deposited on silicon substrates using reactive magnetron sputtering Ti 80Si 20 composite target in an argon and methane gas mixture. The structures of the films were analyzed by X-ray photoelectron spectroscopy and Visible Raman spectroscopy. The morphologies were observed by atomic force microscope. The friction coefficients of the films were tested on the ball-on-disc tribometer. The results indicate that the sp 3/sp 2 ratios in the films can be varied from 0.18 to 0.63 by changing Ti and Si contents at various CH 4 flow rates. The surface of the films becomes smoother and more compact as the CH 4 flow rate increases. The lowest friction coefficient is as low as 0.0139 for the film with Ti of 4.5 at.% and Si of 1.0 at.%. Especially, the film exhibits a superlow value ( μ < 0.01) under ambient air with 40% relative humidity in friction process. The superlow friction coefficient in ambient air may be, attributable to synergistic effects of a combination of Ti and Si in the film.