Zirconium oxynitride (ZrNO) films were deposited by RF reactive magnetron sputtering in water vapour–nitrogen atmosphere varying the deposition temperature from RT to 600 C. Optical analysis, x-ray diffraction, x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) are the employed characterization techniques to investigate the influence of the substrate temperature on the films physical properties. It was found that the variation of the substrate temperature from RT to 600 C caused a structural transition from cubic phase of Zr 2 ON 2 to ZrN one, as confirmed by TEM observations too. In particular, Forouhi–Bloomer dispersion equations for optical parameters (n and k) and deconvolution of XPS spectra allowed further chemical properties be elucidated. They also permitted identification of two oxynitride phases, γ phase (E g= 1.94 eV) and β phase (E g= 1.7 eV), and an over …