Synthesis and characterization of Mg x Zr 2− x N 2 (0.5≤ x≤ 1.8) thin films deposited by reactive magnetron co-sputtering in nitrogen plasma is reported. Composition measurements show that nitrides with low oxygen content (less than 1%) can be formed up to x= 1.0, at which point an increase in oxygen content is observed. Up to composition of x= 1.6 the Mg x Zr 2− x N 2 thin films form in a rocksalt-derived crystal structure, as revealed by X-ray diffraction measurements. At x> 1.6 the films rapidly oxidize. The lattice constant of the stoichiometric MgZrN 2 composition is a= 4.537 Å, and only small changes in lattice parameter are observed with changing composition. Electrical conductivity decreases by several orders of magnitude with increasing Mg-content. The conductivity of Mg-rich (x≥ 1) films increases with increasing measurement temperature, indicating semiconducting character of Mg-rich Mg x Zr 2− x N 2. Optical absorption measurements of these Mg-rich samples show a clear absorption onset at 1.8 eV, also indicative of semiconducting behavior.