A series of new polyesters was synthesized by high-temperature solution condensation of 1,6-diamantanedicarboxylic acyl chloride with aromatic diols in o-dichlorobenzene. The polyesters had inherent viscosities of 0.20-1.50 dL/g and were obtained in high yield. Diamantane-containing polyesters IIIa, IIIb, and IIIc show secondary transitions at low temperatures and a mainly melting transition at around 375 degrees C over a range of -100 to +400 degrees C, but no glass transition was observed by DMA. Particularly, a step in modulus at the beta transition at around 60 degrees C was also observed in diamantyl-containing polyesters. In all cases, these polyesters show a rather high G’ value (about 10(8) Pa) up to 350 degrees C. The 5% weight loss temperatures of these polyesters were in the range 403-451 degrees C in nitrogen. The melting temperatures of polymers IIId, IIIe, and IIIf were 429, 369, and 395 degrees C, respectively. The glass transition temperature of IIId was 267 degrees C. Polymers IIIa, IIIb, and IIIc were soluble in o-chlorophenol and could be cast into transparent, tough, and flexible films. Their cast films had a tensile strength at break up to 80.5 MPa, an elongation to break up to 15.1%, and an initial modulus up to 1.6 GPa. The dielectric constants of polyesters IIIa, IIIb, and IIIc ranged from 1.3 to 1.9.