A series of novel crosslinkable, highly fluorinated polyesters were synthesized by copolycondensation reactions of terephthaloyl chloride with 4, 4'-(hexafluoroisopropy-lidene)-diphenol and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-octane-1,8-diol, followed by reaction with 2-hydroxyethyl methacrylate. The resulting polyesters with the molecular weights (M-n: 12,100-20,000 g mol(-1)) and polydispersities (1.49-2.25) were useful for the fabrication of polymer optical devices because of their good solubility in common organic solvent and the processable flexibility. The ratios of the components of the polyesters were characterized by FTIR and NMR. The polyesters had high glass transition temperature (T-g,T- : up to 170 degrees C) and good thermal stabilities (T-d : up to 470 degrees C). The refractive index of the polyester film was tuned and controlled in the range of 1.447-1.576 at 1550 nm by monitoring the component fractions during the preparation procedures. Low-loss optical waveguides were fabricated from the resulting polyesters and the propagation loss of the channel waveguides was measured to be around 0.56 dB/cm at 1550 nm. (c) 2007 Wiley Periodicals, Inc.