Polymer electrolyte nanocomposite films composed of PEGDA/LiCF3SO3 with various wt.% Mg-Al LDH-2 fillers were prepared. Gel structure was obtained by thermal crosslinking reaction of residual terminal acrylate groups of PEGDA. The molecular weight of PEGDA was ca. 258, 575, and 700, respectively. The ionic conductivity and mechanical properties of resulting nanocomposites were characterized by impedance measurements, X-ray diffraction, and tensile measurement, respectively. The ionic conductivity was highly enhanced in the nanocomposite systems, which is also increased with increasing molecular weight of PEGDA. It was observed in XRD spectra that the layered structure of Mg-Al LDH-2 was totally exfoliated by the prepolymer. In the case of the composite films having 4.5 wt.% of the Mg-Al LDH-2, the ionic conductivity reached to 1.6 x 10(-3) S/Cm at room temperature. The incorporation of nanoparticle into the gel resulted in the increase in the tensile modulus by two to three times. (C) 2004 Elsevier Ltd. All rights reserved.