Homoleptic tris(η 4-1-oxa-1,3-diene)complexes of tungsten and molybdenum have been prepared in moderate to high yields starting from the α, β-unsaturated ketones 1– 3 and tricarbonyltris(propionitrile)tungsten(0) or from 1 and η 6-benzenetricarbonylmolybdenum(0), respectively. The method is limited to enone ligands without substituents in the β-position. The new crystalline and air-stable yellow complexes have been characterized, and preliminary reactivity studies carried out. Their NMR-spectra show the compounds to have three-fold symmetry.