Postradiation graft polymerization of acrylic and methacrylic acids from solution and the gas phase onto the copolymer of tetrafluoroethylene with vinylidene fluoride has been studied. The dependences of the degree of grafting on the thickness of the films, temperature and grafting time have been obtained. Scanning electron microscopy has been used to study the distribution of the grafted polymer over the section of the samples. From the results some conclusions are drawn on the aspects of the effect of diffusion factors on the gross kinetics of the process. A significant difference in the polymerization rates of acrylic and methacrylic acids was established in identical experimental conditions. The fall observed in the polymerization rate of methacrylic acid is related to the possibility of “occlusion” of the terminal growing radicals established by EST spectroscopy.