The interest about zirconium oxynitrides is growing with the attention for zirconium nitrides phase at high zirconium content. In recent years a great progress has been made to realize both the higher nitride phase (Zr3N4) and the higher oxynitride phase (Zr2ON2) in more ordered crystal structures. In this work the above-mentioned two phases are realized by RF magnetron sputtering technique. The characterization results, illustrated in the present paper, push towards the evidence of an evolution from zirconium N-rich nitride to the oxynitride films by introducing a very small percentage (0.5%) of water vapor in a sputtering atmosphere made only of nitrogen gas. In particular, structural analysis identified zirconium N-rich nitride as c-Zr3N4 and zirconium oxynitride as c-Zr2ON2. The formation of zirconium oxynitride is due to oxygen presence, coming from the water dissociation in the plasma. Both phases request an additional energy supplied by substrate bias assistance for c-Zr3N4 and by more energetic particles reflected by the Zr target for c-Zr2ON2. (C) 2012 Elsevier B.V. All rights reserved.