The technique of the total reflection of x rays has been applied to the study of thin films of Cu, Ni, Ge, and Se vacuum‐deposited onto polished glass substrates. Starting with fresh films, ``smooth'' enough to exhibit pronounced x‐ray interference fringes in the region just beyond the critical angle, the effects of vacuum anneal and oxidation were studied. Changes in the reflection curves are interpreted in terms of possible structural changes in the films. Reflection from layers of particles of carbon or polystyrene latex deposited onto ``smooth'' substrates was also studied for comparison.