AbstractThermolysis of diphenyl disulfide in the presence of iodoarenes yielded the corresponding unsymmetric diaryl sulfides. This new reaction has been utilized for the synthesis of high molecular weight poly(phenylene sulfide) and poly(naphthylene sulfide)s, starting from bis(4‐iodophenyl) disulfide and bis(iodonaphthyl) disulfides. Poly(phenylene sulfide) with a melting temperature above 250 °C was also obtained from bis(4‐bromophenyl) disulfide in the presence of a suitable reducing agent (e.g. potassium iodide). Heating bis(4‐chlorophenyl) disulfide afforded only a low molecular weight polymer. Bis(4‐fluorophenyl) disulfide remained stable under the same thermolysis co