An improved overall process is provided wherein poly(bisbenzimidazobenzophenanthroline) is formed on an expeditious basis and is recovered from the reaction mass in substantially pure form. Appropriate quantities of 1,4,5,8-tetracarboxy naphthalene dianhydride and 3,3',4,4' -tetraaminobiphenyl are condensed as defined) in a reaction zone while dissolved in molten antimony trichloride, and the resulting reaction mass containing the dissolved product is discharged into a precipitation zone containing hydrochloric acid (as defined). The resulting solid product is separated and dried. The liquid portion which is separated from the solid product contains antimony trichloride dissolved in hydrochloric acid and is subjected to distillation which substantially separates these components. The antimony trichloride is recycled to the reaction zone, and the hydrochloric acid is recycled to the precipitation zone.