Oligomeric polyester, namely poly(tetramethylene asparate) (PTMA), was synthesized From D,L-aspartic acid and 1,4-butanediol by a melt codensation technique. Polyester-metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Fe(III), Pd(IV), and UO2(II) in DMSO. The polyester-metal complexes were characterized by elemental analysis, UV-Vis, IR spectral studies, magnetic susceptibility measurements and H-1-NMR. Mossbauer spectra of mixed samples of Pd-PTMA and Fe(II)-PTMA with a ratio of 1 : 2 mol showed the iron(III) oxide formed in early stages of the decomposition at 250degreesC is mainly fine-grained and as the temperature is increased, well-crystalline hematic is formed. Above 250degreesC, the Mossbauer spectrum showed the typical six-line pattern of magnetically oriented Fe(III) oxide, but at 800degreesC, the spectrum showed quadrupole interaction characteristic of PdFe2O4, spinel. The metal ions were found to be six-coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (DTA-TG) showed that co-ordination polymers are thermally more stable than polyester; the activation parameters for both decomposition steps were calculated and discussed. (C) 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 942-947, 2004.