Hybrid electrolytes produced by the sol–gel process were obtained by doping a di-urea cross-linked POE/ siloxane hybrid host framework (d-U(2000)) with lithium hexafluoroantimonate (LiSbF 6). Flexible, transparent xerogel films with ∞ > n ≥ 2.5 (where n, composition, represents the molar ratio of oxyethylene units OCH 2 CH 2 per Li + ion), thermally stable to at least 200 °C, were prepared. At 30 °C the highest ionic conductivity of all the electrolytes prepared was 1.32 × 10 − 5 S cm − 1 for n = 30. The electro-chemical stability windows of these materials span at least 6.0 V. Samples with n b 200 are amorphous, ho-mogeneous and non-porous. Crystallites of POE are formed in the most dilute electrolyte (n = 200). The guest Li + ions were shown to coordinate to the oxygen atoms of the urea carbonyl groups over the entire range of salt concentration. The great majority of the SbF 6 − ions interact with the Li + ions. Contact ion pairs were detected only at n = 200. Trace amounts of "free" anions exist in all electrolyte samples.