Tungsten oxynitride films (WOxNy) were deposited with a chemical composition in the range of 0 < x < I and 0 < y < 1. For the W-N system, the alpha-W, beta-W, and beta-W2N phases were identified according to the amount of nitrogen. In the W-O-N system the structure depended on the amount of oxygen. For an oxygen fraction, f(O2) = C-O/(C-O+C-N), smaller than 0.46 the beta-W2N phase is evident, whereas above that value the structure became amorphous.