The effect of addition of nanoparticle inorganic oxides to poly(ethylene oxide) (PEO) complexed with LiClO₄ on cation transport properties has been explored by electrochemical and ⁷Li nuclear magnetic resonance (NMR) methods. The presence of the nanoparticles generally increases the ionic conductivity and the cation transference number, the effect being greatest for TiO₂. The enhancement in cation transference number is directly correlated with increased Li diffusivity measured by NMR. The NMR results also demonstrate that the increased ionic conductivity is not attributable to a corresponding increase in polymer segmental motion, but more likely a weakening of the polyether-cation association induced by the nanoparticles.