The transmission of thin films of the following materials has been measured between 400 cm−1and 3000 cm−1: Cellophane, ethyl cellulose, cellulose acetate, Duco household cement, polystyrene, glyptal, Pliofilm, rubber, Plexiglas, methyl methacrylate polymer, XYSG Vinylite, and Shawinigan V‐15 resin. The possibility of using these materials for windows in spectroscopic experiments is discussed.