Extension of the understanding of properties of films of metals produced on glass surfaces by vacuum evaporation has permitted the fabrication of film-resistance thermometers that with simple instrumentation accurately measure surface or average surface temperatures without altering the geography of that surface. Formerly unknown and unstabled related properties of such films have been classified and may be anticipated or eliminated by recommended experimental procedures. Films of several of the most chemically inert and refractory metals 300 to 3,000 Å. thick have been shown to attain accuracies as high as 0.01°C. for practical periods of time. Their use, which is described, is developing satisfactorily, and the technique and equipment for their preparation are relatively simple.