Ionically conducting materials based on a poly(ɛ-caprolactone) (PCL)/siloxane organic/inorganic host framework doped with magnesium triflate (Mg(CF3SO3)2) were synthesized by the sol–gel process. In this matrix short PCL chains are covalently bonded to the siliceous network via urethane linkages. In this study the salt content of samples was identified using the conventional notation n, where n indicates the number of (C(O)(CH2)5O) PCL repeat units per Mg2+ ion. Xerogels with compositions ranging from n =∞ to 1 were prepared. The only composition studied that was not entirely amorphous was that prepared with n =1. Xerogels with n ≥7 are thermally stable up to at least 200°C. The composition with the highest conductivity of the series is that with n =34 (5.9×10−9 and 9.8×10−7 Scm−1 at 24 and 104°C, respectively).