The use of Arrhenius plots of total conductivity derived from ac impedance spectroscopy measurements in characterisation of phase transitions is discussed with reference to Bi4V2O11-delta and the BIMEVOX family of oxide ion-conducting solid electrolytes. The technique is shown to be superior in some cases to standard laboratory methods such as thermal analysis and variable temperature X-ray diffraction. Examples include the identification of the metastable intermediate epsilon-Bi4V2O11-delta, beta-phase stability in BIMGVOX and a kinetic study of the gamma ->gamma' transition in BIZNVOX. (c) 2005 Elsevier B.V. All rights reserved.