Individual hard thin film materials such as TiN, SiN1.3, SiC and CNx exhibit attractive mechanical, tribological, optical and electronic properties related to their microstructure and chemical bonding. In the present work, we combine the characteristics of such materials, while systematically studying quaternary thin films prepared by plasma enhanced chemical vapor deposition (PECVD) from TiCl4/SiH4/N-2/CH4 mixtures with different concentrations of CH4. Detailed structural and chemical characterizations using transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and elastic recoil detection suggest formation of a TiCxNy/SiCN nanocomposite structure. Depth-sensing indentation, static indentation and curvature measurements, on samples prepared under optimal conditions, reveal a hardness of 55 GPa, reduced Young's modulus of 302 GPa, a compressive stress of 2.0 GPa, an elastic rebound of more than 80%, H-3/E-r(2) coefficient of 1.8 GPa and a high toughness. The friction coefficient and the wear rate, measured against diamond, are 0.13 * 10(-6) and 12 * 10(-6) mm(3)/Nm, respectively. We compare the properties of the present nanocomposite TiCxNy/SiCN coatings with the performance of PECVD films from our earlier studies: these include TiN/SiN1.3 nanocomposites and SiCN, for which we obtained a hardness of 45 and 33 GPa, and a reduced Young's modulus of 350 and 200 GPa, respectively. (C) 2004 Elsevier B.V. All rights reserved.