We present a study of impedance spectroscopy (IS) under varying loads. An equivalent circuit is proposed taking the deformability and the effect of change in free volume into account, which yields the dc ion-conductivity as well as the Young's modulus from these results. Independent measurements of elastic properties are done and the result is compared with Young's modulus predicted from IS. The sample we studied is PEO-NH4ClO4 with a salt fraction of 0.19 by weight, with frequencies varying in the range of 40 Hz to 3 MHz and loads varying from 400 to 1600 g. (c) 2007 Elsevier B.V. All rights reserved.