In this work, silicon oxynitride (SiOxNy) films with different chemical compositions were deposited by plasma enhanced chemical vapor deposition (PECVD) technique and used as core and cladding hi optical slab and strip waveguides in order to obtain high quality optical devices with low attenuations. The refractive index and optical loss measurements of the PECVD SiOxNy-based waveguides were obtained by a prism coupler system. On the other hand, etching experiments, using a Reactive Ion Etching (RIE) system, were also accomplished in order to define vertical walls on optical strip waveguide structures. The results of the optical characterizations showed that it is possible to obtain slab waveguides with optical loss as low as 0.4 dB/cm depending on the chemical composition of the core and cladding layers. In this way, the feasibility of using SiOxNy films for the fabrication of optical waveguide structures is demonstrated.