A(+)-ion conducting composites based on silver-borate glasses and alpha-Al2O3 ceramic matrices were synthesized by a high-pressure method (P = 7.7GPa and t = 100-200 degrees C). They exhibited improved mechanical properties (e.g. reduced brittleness). Their electrical conductivity, as well as the conductivity of the corresponding glasses was measured in the wide temperature range from -190 to +30 degrees C. It was found out that for all measured samples (composites and glasses) the temperature dependence of the conductivity follows the Arrhenius formula with a single activation energy close to 0.30eV in the whole temperature range. The conductivity of the composites is lower than that of the corresponding glasses by a factor of 5-10, due to percolation phenomena. It was found out that by an appropriate thermal treatment, the conductivity of the composites can be raised to ca 2.10(-3) S.cm(-1) at room temperature. (c) 2008 Elsevier B.V. All rights reserved.