A new solution series of bismuth vanadate of the molecular formula Bi4CdxV2-xO11-delta; 0 <= x <= 0.25 was synthesized by solid state reaction, via substitution of Cd for V in the parent compound, Bi4V2O11-delta-. The sample characterization and study of the phase transition changes were performed by using XRD, FT-IR and DSC measurements. It has been found that the ionic conducting, tetragonal gamma-phase could effectively be stabilized to room temperature for x=0.175 solid solution. Impedance spectroscopy (IS) measurements proved that the oxide ionic conductivity predominantly arises from the grain contribution. In addition, highest ionic conductivity (similar to 1.30 x 10(-4) S cm(-1) at 420 degrees C) was observed for x=0.20 solid solution with less pronounced thermal hysteresis. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.