Abstract: The present application relates to a process for the manufacture of transparent, large band gap, high refractive index and high temperature stable, non-stoichiometric titanium nitride thin film (TiNx0.1<x?1.0) for optical and optoelectronic devices comprising the steps of preparing the said film by magnetron sputtering in a mixture of argon and nitrogen atmosphere, as a thin layer on a substrate selected from stainless steel, amorphous fused silica, magnesium oxide, lanthanum aluminate and sodium borosilicate glass, the deposition of the said layer of the substrate being carried out at temperature between ambient and 873 K, the deposition being controlled by varying the nitrogen pressure. The invention also provides films prepared by this process and substrates coated with such films.