The modification of polymer track membranes from polyethylene terephtalate (PET) and polypropylene (PP) was performed by radiation-induced graft polymerization of thermosensitive poly-N-isopropylacrylamide (poly-NIPAAM). The opening and closing of the pores was controlled by temperature and studied by the electric conductivity and water flow methods. The structure of the grafted membranes was investigated by scanning electron and atomic force microscopy.