Mo-N films were deposited on glass or silicon wafers by reactive sputtering. The growth rate, composition, microstructure, and sheet resistance of the films were analyzed and determined to be controlled by deposition power as well as by N-2 partial pressure. Grain refining. which increases the sheet resistivity of Mo-N films, was observed at higher N-2 partial pressure as well as at lower deposition power input. tau-Mo2N was achieved at suitable conditions. We propose that the films formed by the reaction of nitrogen and Mo atoms on the substrate surface.