A process for purifying a polycarbodiimide comprising (a) providing a mixture comprising a polycarbodiimide and a carbodiimidization catalyst; (b) separating carbodiimidization catalyst from the polycarbodiimide by subjecting the mixture according to (a) to a first distillation, (c) adding an entrainer to the first bottom product obtained from (b) to obtain a mixture; (d) further separating carbodiimidization catalyst from the polycarbodiimide by subjecting the mixture obtained from (c) to a second distillation.