Bismuth oxide in its delta-phase (high-temperature fluorite structure) is a well-known solid electrolyte owing to its high oxygen ion conductivity. In this work, delta-Bi2O3 thin film was stabilized at room temperature by electrodeposition on different conductor substrates. Electrodeposited thin films have a good quality with an excellent adhesion to the substrate. The crystalline structure and the stability of the deposit were studied by Xray diffraction (XRD). Both XRD measurements and transmission electron microscopy (TEM) investigation revealed the nanocrystallinity of the films. XRD measurements showed a decrease of nanocrystallites size after thin film annealing. The resistivity measurements showed an excellent conductivity of electrodeposited delta-Bi2O3 thin films with an ionic conductive behaviour and an electrical conductivity value close to the theoretical value: the thin film deposited on a gilded silver substrate exhibit a conductivity of 0.39 S/cm at 440 degrees C. (C) 2007 Elsevier B.V. All rights reserved.