The possibility of the recovery of hydrochloric acid from rare earth (RE) chloride solutions was first experimen-tally studied by batch vacuum membrane distillation (VMD). The recovery by continuous VMD was also studied to devise methods that enabled the operation of VMD setup in a stable condition as well as to increase the membrane-operating life The results indicated that HCl separation with RE by VMD was possible, and the recovery ratio of 80% could be achieved by batch VMD. In continuous VMD, when the temperature of circular solutions, circular rate, and downstream pressure was 62-63°C, 5.4 cm/s, and 9.33 kPa, respectively, the HCl concentration in circular solutions and the processing capacity per membrane area were obtained. The mathematical results were in accordance with the experimental ones. The possibility of the recovery of hydrochloric acid from rare earth (RE) chloride solutions was first experimen- tally studied by batch vacuum membrane distillation (VMD). The recovery by continuous VMD was also studied to devise methods that enabled the operation of VMD setup in a stable condition as well as to increase the membrane-operating life The results indicated that HCl separation with RE by VMD was possible, and the recovery ratio of 80% could be achieved by batch VMD. In continuous VMD, when the temperature of circular solutions , circular rate, and downstream pressure was 62-63 ° C, 5.4 cm / s, and 9.33 kPa, respectively, the HCl concentration in circular solutions and the processing capacity per membrane area were obtained. The mathematical results were in accordance with the experimental ones.