Alkaline solid electrolyte membranes, based on the poly(vinyl alcohol) (PVAL), lithium hydroxide (LiOH) and water with various salt concentrations have been synthesized. These systems have anhydridous ionic conductivity (σ) as high as 2,9 × 10–4 Scm–1 at room temperature and show a linear dependence of ln(σ) with 1/T below 80 °C. The thermal analysis indicated three transformations in the blends: at 205, 150 and –125 °C, associated with decompositions, melting point and glass transition of the polymer blends, respectively. The X-ray spectra for the samples at room temperature show a peak at about 2θ = 20° for all salt concentrations and whose intensity depends on the amorphous character of the system. The results are discussed in terms of the high mobility of the Li+ ions in the amorphous phase of the complex. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)