Abstract: A method of separating potassium chloride and sodium chloride from a heated solution of these salts, such as a solution obtained from potash ore, to recover potassium chloride from the ore is disclosed. The method includes a combination of steps of (a) extracting water from a heated solution containing potassium chloride and sodium chloride using a membrane system and (b) subsequently cooling the solution discharged from the membrane system, whereby steps (a) and (b) make it possible to selectively recover potassium chloride and sodium chloride from the solution.