The feasibility of using copper nitride and tin nitride thin films as write‐once optical recording media was explored. The Cu3N and SnNxfilms were obtained by the reactive sputtering method. They were thermally decomposed into Cu and Sn films at 470 and 550 °C, respectively. The Cu film obtained by the thermal decomposition showed a large difference in reflectance which is applicable to the optical recording media. The Sn film obtained by the thermal decomposition included SnO, and consequently it showed a small difference in reflectance from that of SnNxfilm. ©1996 American Institute of Physics.