Very recent measurements of the electrical conductivity of solid systems AgX-CdX2 (where X Cl, Br) that form large areas of solid solutions, have shown that maximum conductivity occurs for a concentration around 20 mol% of the cadmium halide. Here, we suggest a quantitative explanation of this phenomenon based on a model that was recently suggested (J. Appl. Phys. 103, 083552, (2008)) for estimating the compressibility of multiphased mixed crystals. In addition, explicit conditions are obtained which predict when such a conductivity maximum is expected to occur. (C) 2010 Elsevier B.V. All rights reserved.