Very thin CoSi2 films, epitaxially grown on silicon (111) surfaces, have been obtained under ultrahigh vacuum conditions by thermal reaction of Co layers deposited onto Si (111) substrates. The morphology and structural properties of the CoSi2 films depend strongly on experimental parameters such as film thickness, annealing temperature to form CoSi2, or substrate temperature during Co deposition. Usually for high‐temperature formation (≥700 °C) and large thickness (≥200 Å) CoSi2 islands are observed. Below these limits the CoSi2 films display a rather smooth and homogeneous aspect. The reaction kinetics are also followed in situ monitoring the Co and Si Auger peaks versus annealing temperature. Two interfaces have been examined, namely Co–Si and Co–CoSi2. Plateaus in the Auger peak variation show the evolution of the sampled region from the Co metallic phase to successively Co2Si, CoSi, and CoSi2 phases. Finally, electrical characteristics of some nearly perfect CoSi2–Si Schottky barriers have been checked with intensity and capacitance versus voltage techniques. The deduced barrier ranges around 0.65±0.02 eV and no signal has been detected with deep‐level transient spectroscopy.