High melt viscosity poly (phenylene sulfide) (PPS) can be prepared via melt condensation of p-iodophenyl disulfide analogous to the solution condensation previously reported by other investigators. Depending upon reaction conditions, the material contained varying amounts of gels, whereas under all conditions, anywhere from 1 to 3 mol % disulfide linkages were present. Solution in 1-chloronaphthalene allowed separation of soluble and gel fractions and also cleaved the disulfide linkages, which allowed better quantitation of the disulfide content than did elemental analysis. Cleavage of the disulfides with 1-chloronaphthalene was verified via a model reaction. Branching in the preparations was related to the level of iodine in the melt reaction and also the reaction temperature. A branching mechanism is proposed based on model experiments that showed a complex reaction order and an initial rate of branching that was dependent on iodine concentration.