Seven 1,3,4-thiadiazole-containing polyethers with reduced viscosities of 0.27-1.44 dL/g were synthesized by the high-temperature solution polycondensation of novel activated difluoride, 2,5-bis(4-fluorophenyl)-1,3,4-thiadiazole, with aromatic diols possessing a variety of ring structures. The expected chemical structures were confirmed by IR and H-1-NMR spectroscopy and elemental analysis. Of all the polymers, three polyethers were highly crystalline and soluble only in limited solvents such as concentrated sulfuric acid. The other polyethers were amorphous and dissolved easily in a variety of organic solvents including N-methyl-2-pyrrolidone (NMP), phenols, and chlorinated hydrocarbons. Colorless to slightly yellow-colored, transparent, and tough films could be cast from the NMP solutions of the amorphous polyethers. The mechanical properties of the films were excellent, and their tensile strength, elongation at break, and tensile moduli were in the ranges of 48-72 MPa, 5-7%, and 1.3-1.9 GPa, respectively. The amorphous polyethers had high glass transition temperatures of 204-299 degrees C. All the polyethers were highly thermally and thermooxidatively stable and exhibited no weight loss up to 400 degrees C, with 10% weight loss being recorded at 464-513 degrees C in air.