In the past few years, considerable effort has been put into the development of stable proton-conducting systems consisting of a strong acid dissolved in a solvent entrapped in a polymer gel. There has been continuing interest in orthophosphoric acid dissolved in aprotic solvents such as propylene carbonate (PC) and N,N-dimethyl formamide (DMF), which are contained in methacrylate-based polymer gels. In this report, we present the results of a study of those phosphoric acid-solvent-methacrylate-based polymer gel electrolytes that have ionic conductivities above 5 x 10(-4) S.cm(-1) at ambient temperature. FT-IR, FT-Raman, and high-resolution NMR spectroscopies are used. The objective is to understand better the interaction of orthophosphoric acid with the solvent and the polymer gel to gain information on possible proton-conduction mechanisms.