Single-crystal palladium, chromium and gold films with (100) orientation were made by electron beam evaporation of the metal onto a rock-salt substrate maintained at about 400°C. Subsequently, an amorphous silicon film was deposited at room temperature onto the metal film in the same pump-down to form a reaction couple. Reactions between the amorphous silicon and the single-crystal metallic films were studied by transmission electron diffraction and microscopy. We found that metals such as palladium and chromium which form silicides react uniformly over the entire interface with the silicon, but gold which forms no stable silicides shows a non-uniform interfacial reaction. The nucleation and growth rate of silicon crystals in the Au-Si reaction was measured.