Fabrication, microstructure, chemical bonding and composition, and optical properties of zinc nitride films are investigated in this work. The films were deposited by reactive magnetron rf sputtering of zinc in N2-Ar ambient. Based on X-ray diffraction data, the as-deposited films are polycrystalline with cubic zinc nitride structure and (400) preferred orientation. Well defined Zn-N, N-N, as well as Zn-O and H-O bonding configurations are revealed by X-ray photoelectron spectroscopy data. The as-deposited films are found to be almost-stoichiometric and contain only a small fraction of oxygen. A direct band gap of 1.5 eV is obtained by using the photon energy dependence of the optical absorption of the films. This result is confirmed independently by spectroscopic ellipsometry.