The alternating copolymer of ethylene and carbon monoxide (POK) has propel ties that suggest possible utility for fibers. However, in order to be melt spinnable, the copolymer should be stable somewhat above its melt temperature for some minutes. Research to improve the stability of POK was carried out by (1) preparation of hydrogen-bonded polymer blends; and (2) addition of plausible stabilizers, individually or in combinations. To study thermal stability above the polymer melting range, FTIR,TGA, and DSC measurements were used. These studies allowed us to distinguish DSC as an effective method for evaluation of melt-spinning capability. Four DSC evaluation criteria, best suited for selection of stabilizer candidates, were determined for use in the present study but may have broader applicability. In approach (1), phenolformaldehyde oligomers or poly(4-vinylphenol) showed only a small benefit in crystallinity retention. Most of the effort was put into approach (2). The IR and TGA studies pointed to furan ring formation as an important decomposition mode, and we considered this reaction likely to be catalyzed by acid. Catalyst residues and traces of metals, introduced during processing, were also believed likely to cause degradation. Classes of stabilizer candidates explored comprised acid scavengers, ligands, antioxidants, selected inorganic compounds, and derivatives of cellulose. The best results were found with aromatic carbodiimides, mono- and polyepoxy compounds; beta-diketones and cellulose ethers, and especially combinations of the preceding compounds with calcium hydroxyapatite.