Abstract A series of metal ion-bis-(β-diketone) polymers containing beryllium, copper(II), nickel(II), zinc(II) or cobalt(II) have been prepared by four different methods. Three types of structures are postulated on the basis of elementary analysis of the polymers. The thermal stability of the polymers was studied by a relatively simple method, utilizing a thermogravimetric balance. It was found that, in general, the order of thermal stabilities is Be(II) > Cu(II) > Ni(II) > Zn(II) > Co(II). The polymers derived from bis-(benzoylacetones) and bis-(dibenzoylmethanes) are thermally more stable than those derived from the corresponding bis-(acetylacetones). Similarly, the polymers derived from bis-(β-diketones) containing no connecting link between the diketone groups are thermally more stable than the polymers derived from the corresponding bis-(β-diketones) which contain a connecting link. The stabilities depend upon this connecting link in the following order: . The beryllium polymers do not all conform to these generalizations.