Photoinduced graft polymerization of N-vinylimidazole (VI) and graft copolymerization of N-vinylimidazole with acrylic acid (AA) onto track-etched polyethylene terephthalate membranes (PET TeMs) with a pore diameter of 450 +/- 15 nm have been systematically studied. The effect of different parameters, such as irradiation time, monomer concentration, and solvent nature, has been examined. The samples have been characterized using the instrumental techniques of FTIR and XPS spectroscopies, thermogravimetry, and scanning electron microscopy. The copolymer composition has been determined spectrophotometrically using the Toluidine Blue and Acid Orange dyes. Optimal conditions of AA and VI copolymerization have been found. It has been shown that the surface of modified PET TeMs is reach in functional groups which makes them a promising material for the development of nanosensors and nanocatalysts.