Poly(ethylene oxide) films with different concentrations of sodium triflate were prepared by the usual solvent casting process in anhydrous conditions. Structural characteristics for each salt concentration were identified using x-ray photoelectron spectroscopy (XPS) for the first time. Further, thermal and x-ray diffraction techniques were used to characterize the crystalline and amorphous phases and to correlate these data with the results obtained with x-ray photoelectron spectroscopy. The interaction between poly(ethylene oxide) (PEO) and sodium triflate in the concentration range of n = 128, 64, 32 16, 8, and 4 in the general formula (PEO)(n)-NaCF3SO3 is described. The XPS-studies reveal a characteristic interaction of the -C-C-O- chain of PEO with the cations of NaCF3SO3 for each salt concentration. The interaction results in a rearrangement of the -C-C-O- chain which is strongest in PEO(16)NaCF(3)SO(3).