The separation of hafnium and zirconium, required for nuclear use of zirconium, is generally performed by liquid-liquid extraction in organic solvents. The paper describes a new process based on extractive distillation of zirconium chloride (ZrCl4) and hafnium chloride (HfCl4) in a solvent made of molten potassium chloride-aluminum chloride (KCl-AlCl3) mixture above 350°C at atmospheric pressure. The corresponding process is now in full-scale industrial production.