A method has been developed for the synthesis of semicrystalline poly(arylene ether ether sulfide) materials by first preparing a soluble, amorphous sulfoxide containing precursor, then rapidly reducing the sulfoxide moiety to sulfide. The sulfoxide polymers are synthesized using conventional nucleophilic aromatic substitution reactions between difluorodiphenyl sulfoxide and diphenols. Reduction of the poly(ether ether sulfoxide)s with oxalyl chloride in conjunction with an iodide salt provides quantitative conversion of sulfoxide to sulfide within seconds, and the insoluble, semicrystalline poly(arylene ether ether sulfide) precipitates in the form of fine particles. Using this soluble precursor approach for preparing semicrystalline material allows there to be good control of molecular weight and end group structure.