The interaction of amorphous MoNixalloys with silicon has been investigated by glancing‐angle x‐ray diffraction, Auger‐electron spectroscopy, and sheet‐resistance measurements in the temperature range 500–700 °C. Mo‐rich alloys (Mo80Ni20and Mo65Ni35) were found to react with silicon at ∼550 °C while nickel‐rich alloys (Mo32Ni68) react at ∼500 °C to form silicides. In Mo‐rich alloys, the initial reaction occurs due to out‐diffusion of nickel from the alloy and in‐diffusion of silicon into the alloy, while in nickel‐rich alloys the initial reaction occurs due to out‐diffusion of nickel only. In the initial phase of the reaction, a mixture of several crystalline phases of molybdenum and molybdenum and nickel silicides is observed. At higher temperature, however, a two‐layer structure MoSi2+NiSi(NiSi2)/ NiSi(NiSi2)/ Si(100) is formed in both cases.