Researches of electrodialysis conversion of HReO₄ from KReO₄ have been realized in collecting conditions. Process has been realized in three-cell pilot electrodialyzer, divided by membranes of MA-41 type of (anionite) and MK-40 (cationite). Initial rough KReO₄ has been preliminary recrystallized. Process control has been realized using conductometric method and chemical analysis. Quality of final HReO₄ has been estimated via precipitation of NH₄ReO₄ according to existing technical conditions for ammonium perrhenate. Clean solutions, containing up to 400 g/l of HReO₄ have been obtained as the result of realized synthesis. At the same time it has been shown, that it is more expedient to realize collected electrodialysis up to 200 g/l concentration of HReO₄. It is defined by supra-proportionally consumption of electric power with raising of HReO₄ concentration up to 200 g/l.