The adsorption of closo-1,2 dicarbadodecaborane (orthocarborane) on evaporated cobalt thin films has been investigated by combined photoemission and inverse photoemission studies. The adsorption of these icosahedral molecules does not strongly perturb the electronic structure of the underlying cobalt. As was previously observed with adsorption on Cu(100), electron induced decomposition of adsorbed orthocarborane decreases the HOMO-LUMO gap. The X-ray photoemission spectra before and after orthocarborane adsorption confirm that the interface with cobalt is abrupt. These results suggest that chemical vapor deposition, via the decomposition of orthocarborane, may be an effective method for fabricating dielectric barrier layers, without utilizing oxides. This is of interest for spin electronics applications.