Bi4-xMxV2O11 (M = La, Gd) was prepared by solid state reactions. The amount of La and Gd in the (Bi4-xMxV2O11) was varied in the range of (0 <= x <= 0.4). The addition of La and Gd to Bi4V2O11 electrolyte Was found to stabilize the beta crystalline phase for x <= 0.3. In addition, the phase transition corresponding beta- to gamma-phases are evident in the ionic conductivity plots as well as in XRD, DSC profiles of x >= 0.3 samples. The highest ionic conductivity was observed in Bi3.9La0.1V2O11 and Bi3.8Gd0.2V2O11 samples in the range of 10(-3)-10(-4) S/cm for 700-500 degrees C. These results were supported by impedance spectroscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). (C) 2009 Elsevier B.V. All rights reserved.