Fluorite oxides Ce0.8Y0.18M0.02O2 (-) (delta) (denoted as MYDC for M = Ca, Sr, Fe and La), were prepared by the sol - gel method used as electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). X-ray diffraction data show that all the compositions were obtained with highly phase-pure cubic fluorite structure. The relatively density of all the samples sintered at 1400 degrees C is more than 95%. Surface morphology has been studied by scanning electron microscope showing a dense microstructure. AC impedance spectroscopy measurements have been carried out to study the ionic conductivity of the samples in the temperature range 400-800 degrees C. In all composition, Ce0.8Y0.18La0.02O2 (-) (delta) shows the maximum conductivity of 0.057 S/cm at 800 degrees C and shows a good prospect of application in IT-SOFCs. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.