A novel class of wholly aromatic poly(ester-imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32-0.49 dL g −1 was prepared by the diphenylchlorophosphate-activated direct polyesterification of the preformed imide-ring-containing diacid, 4-p-biphenyl-2,6-bis(4-trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6-bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) • C. The 10% weight loss temperatures (T 10% ) from thermogravimetric analysis curves were found to be in the range 433-471• C in nitrogen. Films of the polymers were also prepared by casting the solutions.