Thin films of FexAlyhave been grown by molecular‐beam epitaxy on InP(100) substrates. Before growth of the epitaxial intermetallic alloy a 0.2‐μm InAlAs buffer and a ten‐layer AlAs diffusion barrier were deposited. Initial films were grown at 200 °C and were stable up to at least 600 °C. Upon the initiation of growth the reflection high‐energy electron diffraction intensity was observed to decrease slowly and then exhibited oscillations corresponding to layer‐by‐layer growth. There was a short incubation period before the onset of the intensity oscillations that depended upon the ratio of the Fe and Al fluxes. The shape of the specular beam was measured versus incident angle and indicates that the surface is nearly as smooth as the starting AlAs surface. Upon heating to 550 °C the beams became sharper yet. Growth on the annealed surface at 200 °C gave intensity oscillations that were an order of magnitude stronger. Initial attempts to grow epitaxial AlAs on top of the FeAl layer showed three‐dimensional island growth.