Phase-transfer catalytic porous polyethylene membranes, prepared by gamma-ray irradiation grafting of 4-vinyl pyridine and quaternization, were tested in nucleophilic substitution reaction. The effects of grafting conditions (irradiation dose, 4-vinyl pyridine concentration) and quaternization parameters (temperature, time, concentration of reagent) were investigated, It was found that, the grafting degree initially increases with irradiation dose or 4-vinyl pyridine concentration and then decreases. The ion exchange capacity and quaternization ratio of membranes rise with quaternization temperature, time, and reagent concentration. The quaternized membranes exhibit good phase-transfer activity in nucleophilic substitution reaction between n-bromooctane and KI aqueous solution. The n-bromooctane conversion and the observed reaction rate constant rise with the increase in ion exchange capacity of membranes or reaction temperature. This paper provides a novel and promising method for phase transfer catalysis. (C) 2013 Elsevier B.V. All rights reservect.