A series of compact materials has been prepared from two components: an ionically conducting (via Ag ions) 30AgI center dot 35Ag(2)O center dot 35P(2)O(5) glass (denoted as I) and an electronically conducting 90V(2)O(5)center dot 10P(2)O(5) glass (denoted as E). They were ground and sieved in order to separate three fractions varying in grain size: 90 divided by 100 mu m, 60 divided by 90 mu m and 32 divided by 60 mu m. The powdered components were mixed in 1:1 volume ratio and pelletized under pressure. As a result, a series of heterogeneous mixed conductors has been obtained. The aim of the study was to establish a correlation between their microstructure (namely grain size) and electrical properties with a particular focus on their charge storage ability. X-ray diffractometry and DSC analyses confirmed the amorphoPsness of the investigated materials. Electrical properties were investigated by means of DC Hebb -Wagner polarization method and galvanostatic cycling. It was observed that the stored charge increased with the decrease of grain size. It was concluded that the charge storage ability is a synergy effect-a new feature arising from the presence of contact zones between grains of E and I glasses. Possible explanations of this effect were analyzed as well as some preliminary tests were done to evaluate the usefulness of E:I = 1:1 system as an electrode for all -solid capacitor. (C) 2016 Elsevier B.V. All rights reserved.