Functional transition metal oxynitrides (Me-O-N) are emerging materials that are known for their tunable and often enhanced physical properties compared to conventional oxides. As, however, relatively little is known about the Mo-O-N system, this study illuminates the influence of N on the microstructure as well as the mechanical, optical and electrical properties. Mo-O-N films were grown by DC reactive magnetron sputter deposition at different reactive gas flow N2/(O2+N2) ratios. The films change with increasing fraction of N, from an amorphous, transparent and non-conductive with inferior mechanical properties to crystalline, metal-like conductive and hard. Additionally, the film thickness affects the optical and electrical properties.