Abstract: Compositions and processes for forming barrier coatings to prevent hydrogen embrittlement of an underlying material are disclosed. The coating can be made up of composite structures of metal and oxide that are alternately deposited onto a substrate for creating a multilayer coated substrate. Such multilayer coating can be incorporated into many contexts in which hydrogen permeation prevention is desired, such as pipelines and manufacture of advanced automotive steels. The process involves depositing a metal layer onto the substrate followed by a metal oxide layer thereon. The interface of the metal layer and the oxide layer can form space-charge zones that decrease hydrogen permeability therethrough.