The influence of a TiN interlayer on DLC coatings grown on silicon (100), 316 stainless steel and KCl by using the PAPVD pulsed arc discharge technique is presented in this paper. The structure of the coatings was determined by means of FTIR through observation of the absorption band modes of CH2 between 3100 and 2800 cm (1) and representation of the sp(3) and sp(2) carbon bonds, respectively. The sp(3)/sp(2) bonds ratio was calculated by using the base line method and producing a value greater than 1 which was a good prediction of high hardness. XPS analysis of the films was made; the wide spectrum showed the elemental composition of the films (Ti, N, C). A narrow spectrum of C1s at binding energy of 284.48 eV was obtained, and its deconvolution showed peaks of sp(3), sp(2) and Ti-C. Ti-C bonds were formed due to diffusion of carbon atoms into a TiN matrix. The concentration for the XPS spectra was calculated by using the area under the curve of sp(3) and sp(2) peaks. The morphology of the bilayer, including roughness, grain size and thickness was studied through SPM techniques. (C) 2009 Elsevier B.V. All rights reserved.