A new polymer electrolyte based on ethylene oxide unit was synthesized and complexed with lithium salts for high ionic conductivity at room temperature. The salts used were lithium perchlorate and lithium triflate. FTIR and FTRaman spectrosocpies were used to characterize ion-ion or ion-polymer interaction and to determine the relative amount of ions present in the complexes. The spectroscopic analysis was performed as a function of [EO]/[Li+] ratio (20 similar to 5) and temperature (up to 120 degrees C). The free ion percentages in the lithium perchlorate-complexes rapidly decreased to [EO]/[Li+] ratio of 10 and then levelled off. But its ionic conductivity linearly decreased over the salt concentration range studied. The negative temperature dependence of free ion concentration was observed for the lithium triflate-complexes.