A polyoxadiazole polymer is synthesized by heating polyphosphoric acid to a temperature of at least about 160° C. and making a solution by mixing hydrazine sulfate salt with one or more dicarboxylic acids or their derivatives in the heated polyphosphoric acid. The solution is heated under an inert gas atmosphere and the polymer is precipitated in a basic solution. The polyoxadiazole polymer can be produced as a homopolymer or copolymer, and may be used to produce a membrane or fibers.