A method for the preparation of stable metal films on self-assembled monolayer (SAM) substrates is described. The approach combines the functionalization and two-dimensional polymerization of the monomolecular film (see Figure). It opens the way for fabrication of ultrathin SAM insulation layers, which could be engineered into existent and future electronic and spintronic devices to improve performance. The approach should also work for non-metal adsorbates, e.g., pentacene.