The characterisation of transport properties and molecular interactions in two different gel-type polymer electrolytes are described and discussed. The gel electrolytes were based on poly(acrylonitrile) (PAN) and poly(methylmethacrylate (PMMA), respectively, the polymer hosts containing an ethylene carbonate-propylene carbonate (EC-PC) solution of LiClO4. The two systems show comparable conductivities though large differences are developed in the interfacial resistance at the lithium metal electrode. The molecular interactions were investigated using Raman spectroscopy for different salt-solvent compositions. The spectroscopic data are important for the clarification of difference in reactivity towards the lithium metal electrode, and, thus, for the applicability of the two types of membranes in rechargeable lithium batteries.