Commercial microporous hydrophobic polypropylene (PP) membranes were modified by a novel chemical method.This procedure consists of two steps.In the first step,the virgin hydrophobic PP membrane is saturated with acetone; in the second step,the filled membrane is dipped in aqueous KOH solution (d = 1.28 g cm-3).This two-step procedure starts the aldol condensation process of acetone and its products accumulated and adsorbed onto walls of micropores make the membrane hydrophilic.The presented method allow to obtain the hydrophilic PP membrane,persistent and having low electrolytic resistance when soaked with KOH solution.This result was compared with the data obtained with Cellophane.The aldol condensation process of acetone was monitored using the HPLC-ES-MS technique,and modified PP membranes were evaluated by FT-IR and SEM measurements.With the above-mentioned membrane as a separator,silver-zinc cells (with electrolyte KOH,d= 1.40 g cm-3) showed good cyclic life.