Vibrational Raman and Fourier transform IR (FTIR) spectroscopy has been used to determine molecular and ionic interactions in poly(acrylonitrile)-(PAN) and poly(methylmetacrylate)(PMMA) based gel electrolytes, containing LiClO4 salt and a mixture of ethylene carbonate (EC) and propylene carbonate (PC) as a gelating agent. A number of model systems,representing different stages of gel preparation, as well as the pure components, have also been studied. Vibrational spectra reveal interactions between EC and PC molecules in EC-PC mixture via electric dipoles located on C=O groups. In the salt-doped EC-PC system, additional bands close to the ring breathing and bending fundamentals of the carbonate ring of EC and PC, respectively, are attributed to solvent molecules interacting with the cations via Coulombic forces, the satellite band frequencies being well correlated to the cationic potentials. In the PMMA-based gels, no spectroscopically detectable interactions between the polymer matrix and the electrolyte were observed. In the PAN-based systems, in contrast, C=N groups of PAN serve as attractive sites for both the solvent molecules and the cations, the preferable interaction being that between PAN and the solvent.