A process of plasma-initiated grafting of acrylic acid on commercial porous polypropylene membrane was studied. The influence of parameters of the plasma (power, gas pressure, time plasma-sample distance, sample arrangement) and grafting (solvent composition, monomer concentration, time, inhibitor presence) on the degree of grafting, amount of homopolymer produced and surface electrical resistance was determined. A degree of grafting up to 18 mmol/g was obtained, which resulted in sample resistance as low as 30 M Omega cm(2). The molecular weight of AAc homopolymer that can be assumed as equal to the MW of grafted chains, ranged from 25,000 to 50,000,000 da. SEM and water permeability measurements show that grafting causes filling of the pores, which, however, does not stop K+ ions from penetrating the membrane. The performance of nickel-cadmium cells with acrylic acid grafted membranes as separator is also presented. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116:868-875, 2010