Zr(1-x)Mo(x) thin films were deposited by reactive magnetron sputtering with Mo content varying from 0 to 20 at%. GAXRD revealed a gradual shrinkage of ZrN lattice constants as Mo concentration increased while no molybdenum crystalline phases were identified in ZrMoN coatings. XPS data showed a disturbance in ZrN electronic environment due to Mo presence, indicating a substitutional solid solution formation for samples up to 20 at% Mo. Oxidation tests were carried out at 773 K, 873 K and 973 K for all thin films. ZrMoN samples did not maintain the original nitride structure when exposed to such high temperatures. On the other hand, Mo addition in ZrN matrix was favorable to the stabilization of the tetragonal zirconia (t-ZrO2) in preference to the more stable monoclinic zirconia (m-ZrO2) phase at high temperatures.