Gel polymer electrolytes based on a copolymer poly(vinylidene fluoride (VdF)/hexafluoropropylene (HFP)) and a solution of ethylene carbonate (EC), diethyl carbonate (DEC) and as a salt LiN(CF3SO2)2 were prepared by changing the content of the polymer in the range 20–80 wt%. The effects of changing the salt concentration in the solution were also explored. The conductivity was found to vary in the range 10−2 ohm−1 cm−1 (20 wt% of polymer) to 10−8 ohm−1 cm−1 (80 wt% of polymer). Pulsed field gradient (PFG)-NMR was used to determine the diffusion coefficient of lithium (D Li+ )and fluoride species (D F− )and in consequence the transport number. Both D Li+ and D F− decrease with increasing polymer content. Cation transport number (τ +) values between 0.49 and 0.60 were found, depending on the solution content. Pores having average diameter of about 0.5 μm were observed by scanning electron microscopy (SEM).