A series of Al2O3 doped CdI2-Ag2CrO4 composite solid electrolytes was prepared and studied by various techniques. XRD pattern and DTA curve show the presence of AgI component formed due to an ion exchange reaction by following the Pearson's acid base theory. The peaks of XRD and DTA curve became broad after the composite formation. SEM images clarified the presence of multiphase composite. A.C. impedance spectroscopy shows the single semicircle at lower frequency attributed to dominant nature of grain boundary over the grain. The Arrhenius plots of the conductance show a sharp jump at 150 degrees C due to beta -> alpha phase transition and it decreases with increase of Al2O3 content due to partial amorphization of the salt. The conductivity of the composite increases with increase of dispersoid (Al2O3) and displayed maximum value (sigma = 2.49 x 10(-5) S cm(-1) at 30 degrees C) for x = 0.3. The value of dielectric constant was increased by increasing temperature owing to increase in mobility and activity of charge carriers, while it shows the decreasing order with respect to frequency. (C) 2016 Elsevier B.V. All rights reserved.