The compounds LiNiVO4 and LiCoVO4 were prepared by the solid state reaction method at 650 degrees C. The X-ray diffraction patterns of both materials reveal the formation of the inverse spinel structure. Thermogravimetric measurements revealed a reversible mechanism which is attributed to Moisture loss and uptake. Impedance spectroscopy measurements were Carried out at temperatures from 25 to 500 degrees C. Three equivalent circuits were drawn to simulate the materials' electric behavior in each of three temperature ranges, 25 to 175 degrees C, 200 to 300 degrees C and 325 to 500 degrees C. The elements of these equivalent circuits were assigned to three different conduction processes. The activation energy values for the conductivity processes within the grains (bulk conductivity) were found to be 0.24 and 0.29 eV for LiNiVO4 and LiCoVO4, respectively. For grain boundary conductivity two different values were calculated for LiNiVO4, 0.64 and 0.26 eV and one for LiCoVO4, 0.29 eV. In the temperature region 25-150 degrees C a conductance behavior which is not consistent with pure ionic conductivity was observed, since resistance increases up to two orders of magnitude with increasing temperature. This materials' electrical behavior was attributed to a possible protonic conductivity mechanism due to the reversible moisture loss and uptake. (C) 2008 Elsevier B.V. All rights reserved.