In this work the diffusion of sodium-22 was studied in the PEO-PVAc films by means of an autoradiography technique. It is found that the addition of the amorphous PVAc (up to 20 mol.%) increases the effective diffusion coefficients of Na-22 more than one order of magnitude at ambient temperatures. The enhancement is accompanied by a decrease in activation energy. The addition of PVAc increases the disordered amorphous surface layer of the spherulites where the diffusion process occurs at an enhanced rate. With further increasing of PVAc content the distance between large PEO spherulites increases, consequently the share of disordered amorphous regions decreases and the diffusion length of migration changes. It leads to decrease in the diffusion coefficients.