The crystal structure of poly(dithiotriethylene adipate) has been determined through the best fitting of calculated and experimental X-ray diffraction powder profiles. A triclinic cell was found with dimensions a = 4.942 (7) angstrom, b = 4.702 (2) angstrom, c = 20.56 (2)angstrom, alpha = 88.9 (2)degrees, beta = 61.0 (1)degrees, gamma = 67.8 (1)degrees, P-1 space group, and one chain in the unit cell. A full extended trans conformation of the chain fitted satisfactory the experimental data, yielding to a discrepancy factor RP = 0.073. A comparison between the crystal structures of poly(dithiotriethylene adipate) and poly (thiodiethylene adipate) is proposed. (c) 2005 Wiley Periodicals, Inc.