TiCx films with a wide range of C/Ti ratios have been prepared by plasma based ion implantation. The bonding states and structure were investigated as functions of the relative carbon content to titanium. The results of Rutherford backscattering spectroscopy showed that there was more than 20 at.% hydrogen contained in the films. By the deconvolution of X-ray photoelectron core level spectra, the excess carbon was suggested to lead to the formation of interstitial carbon, amorphous hydrogenated carbon (or graphite), polymer-like carbon, and organic compound of titanium. The cross-sectional transmission electron microscopy (XTEM) displayed that the TiC0.81 films mainly consisted of rod-shaped TiC crystal arranged along the growth direction, while the TiC1.55 films contained a relatively random microstructure. XTEM also provided evidence for the existence of amorphous carbon in carbon-rich films, not graphite.