NOVELTY - Method for modifying a porous membrane, comprises impregnating a porous membrane carrier having an open pore structure with a solution (X) comprising a polymer in a solvent in which the polymer is soluble, thus forming the porous membrane carrier impregnated with the polymer solution, and precipitating at least part of the polymer comprised by the impregnated solution from the solution by quenching with a liquid (Y1) comprising a non-solvent for the polymer.    USE - The membrane is useful: in molecular separations and filtration including gas/gas filtration, particle filtration, micro-filtration, ultra-filtration, nano-filtration and reverse osmosis; waste water purification; electrochemical applications including electro-dialysis, electro-deionization, batteries and fuel cells; and controlled release applications including pharmaceutical and nutraceutical components; pertraction, pervaporation and contactor applications; for immobilization of enzymes; and as humidifiers (all claimed). The membrane is useful: in solvent resistant nano-filtration; as biocompatible membranes (e.g. cell macroencapsulation membranes for the encapsulation of islets of Langerhans); and for separation and concentration of solutions and suspensions.    ADVANTAGE - The method increases the hydrophilicity of the porous membrane carrier and/or reduces the average pore size in a controlled manner. The method provides porous membrane with: high porosity; high water flux at very low water pressure; high separation power; good thermal hydrolytic, thermo-oxidative mechanical and dimensional stability; increased stiffness; and excellent resistance against cleaning agents. The method modifies a hydrophobic membrane into a hydrophilic membrane. The method: is simple and economical; can be performed at room temperature and/or at slightly elevated temperature; and does not alter the basic structure of the porous membrane.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a process for preparing a micro-porous membrane, comprising contacting the porous membrane carrier with the solution (X) comprising the polymer, solvent in which the polymer is soluble, and optionally at least one additional component, such that the solution (X) penetrates into the pore structure of the porous membrane carrier, and contacting the porous membrane carrier with the penetrated solution and the liquid (Y1), hence precipitating at least part of the polymer;    (2) the micro-porous membrane obtainable by the process, comprising the porous membrane carrier and the polymeric material intimately divided throughout the porous membrane carrier, where the polymeric material comprises a polycondensation polymer;    (3) a membrane construction comprising a thin micro-porous membrane film, optionally folded, wound and/or supported by a support layer, and/or a hollow membrane fiber, or a bundle of multiple hollow membrane fibers, where thin micro-porous membrane film, respectively the hollow membrane fiber or fibers, consist of the micro-porous membrane; and    (4) a polymer solution comprising an alcohol, water (0.1-30 wt.%), a salt (1-50 wt.%), and a polyamide (0.1-10 wt.%) with a weight average molar mass of 2-100 kg/mole.