In order to introduce more conductive interfaces, the doped ceria-zirconia core-shell nanocomposites are synthesized via a simple and low-cost sol-gel process. Nitrates, citric acid and polyethylene glycol (PEG) are used as starting materials, and the compositions of the core and the shell are Ce0.9Gd0.1O1.95 (GDC) and 8 mol% Sc2O3 doped ZrO2 (ScDZ), respectively, The room-temperature ammonia co-precipitation method is used to prepare the core materials. X-ray diffraction (XRD) indicates that the average grain sizes of the core and shell materials are about 6 nm and 8 nm. The core-shell nanostructure with about 60 nm diameter GDC core (approximate) and about 20 nm thick ScDZ shell, is supported by the field-emission scanning electron microscopy (FESEM) and the transmission electron microscopy (TEM) results. The effects of PEG and the mechanisms during the process of forming the core-shell nanocomposites are discussed in detail. (C) 2009 Elsevier B.V. All rights reserved.