A process for producing disilane from monosilane comprising introducing monosilane into a reaction zone in which the monosilane is subjected to an electric discharge generated by a high frequency current. The monosilane is mixed with at least one inert gas selected from the group consisting of helium and argon. The pressure of the gaseous mixture in the reaction zone is between 0.1 and 3 bar, and the gaseous mixture is contacted in the reaction zone under electric discharge with a wall cooled to a temperature which is sufficiently low for the saturation vapor pressure of the disilane to be negligible, but not low enough for the monosilane to condense at the working partial pressure. Apparatus for conducting this process is provided.