The electrical conductivity of sintered samples of Ce1-xNdxO2-x/2 (0.01 <= x <= 0.2) was investigated in air as a function of temperature between 150 and 600 degrees C using AC impedance spectroscopy. The individual contribution of the bulk and grain boundary conductivities has been discussed in detail. In the low temperature range (< 350 degrees C), the activation enthalpy for bulk conductivity exhibited a shallow minimum at 3 mol% Nd, with a value of 0.68 eV. The activation enthalpy also produced a shallow minimum at 5 mol% Nd in the high temperature range (> 350 degrees C), with a value of 0.56 eV. It was shown that Ce1-xNdxO2-x/2 is an electrolyte that obeys the Meyer Neldel rule. The bulk conductivity data measured by others for the same system has also been recalculated and re-evaluated to facilitate easier comparison with our own data. (c) 2006 Elsevier B.V. All rights reserved.