The reactions of silicon with Ni {001}, Ni {110}, and Ni {111} surfaces have been studied by means of low‐energy electron diffraction. On all three surfaces, at room temperature the silicon atoms are distributed at random and resulting films are amorphous. At temperatures of the order of 300∼400 °C ordered structures are formed: ac(2×1) structure on Ni {001} and ac(8×2) structure on Ni {110}. On Ni {111}, the√3structure that was predicted in a preceding paper is found to occur, but increasing silicon concentration on the surface leads to a 2×2 and then a 2×12 structure, defined in the text, the latter displaying only twofold symmetry. In all cases, the surface concentration of silicon is reduced, at higher temperatures, by the rapid diffusion of the silicon atoms into bulk nickel.