The ethylene oxide-epychloridrine copolymer has interesting properties as an ionic conducting polymer, principally due to its low glass transition temperature (T-g = -40 degrees C). The effect of dopant concentration (LiClO4) was studied by C-13 NMR spectra and conductivity measurements. These studies allowed us to identify the different carbon atoms in the copolymer and their interaction with lithium cations and solvent molecules. The analysis of C-13 spectra and conductivity measurements show that the solvent participates of the solid electrolyte, modifying the charge transport process by the change in the diffusion coefficient.