Abstract: The present invention relates to a process for preparing polypiperazinamide-based reverse-osmosis membranes comprising:(a) preparing a solution of polypiperazinamide in a polar organic solvent;(b) applying the solution on a planar support so as to form a planar body;(c) evaporating the solvent under the action of a flow of air, said air flow having, with respect to said planar support, such a speed as to produce Reynolds numbers between 5 and 100;(d) gelling the planar body by phase reversal by passing through a coagulation bath to form the membrane; and(e) washing the membrane to extract the solvent contained therein. The entire process is carried out at a temperature lower than about 30.degree. C.The invention allows the production of reverse-osmosis membranes with high flow and high mechanical characteristics.