In this paper, a comprehensive X-ray photoelectron spectroscopy (XPS) study of the first atomic layers of TiN nanofilms grown by ion beam assisted deposition on crystalline silicon is reported. This deposition technique allows a fine control of the ion species and energy arriving at the substrate. The substrates are prepared by ion beam cleaning involving Xe+ ion bombardment in different partial pressures of molecular H2. The expected hydrogen passivation effect by the Si-H formation bond limiting the Si-O bonds was quantitatively evaluated and correlated with some retention of H and O at the substrate surface. The effects of molecular H2 and residual H2O atmosphere present during the process on the chemical bonding on both the naked Si substrate and afterward on the interface are reported. A detailed XPS analysis performed in an attached UHV chamber to the preparation chamber of the TiN/Si interface shows that the bombarding cleaning procedure plays an important role in the bond formation at the interface since minute amounts the oxygen jeopardize the bulk properties. (C) 2018 Elsevier B.V. All rights reserved.