The effects of cobalt addition on the sintering, thermal, and electrical properties of Ce0.9Gd0.1O1.95 (GDC) and Zr0.89Ce0.0O2-delta (ScSZ) were investigated. A small addition of cobalt oxide remarkably enhanced the sinterability of GDC, especially for GDC powder with a specific surface area of 40 m(2) g(-1), which was synthesized via a citrate method. Relative densities of approximately 95% can be achieved for GDC pellet samples using 2 mol% Co dopant and sintering at 1100 degrees C for 10 h. The thermal expansion and electrical expansion of 2 mol% Co-doped GDC were comparble to those of the non-doped sample. The thermal expansion of ScSZ with various amounts of Co addition was linear in both oxidizing and reducing atmospheres. The electrical conductivity of Co-doped ScSZ decreased with increasing Co content; however, this decrease was not dramatic. These results Suggest that the addition of cobalt oxide is a promising method for obtaining GDC buffer layers that are sinterable at low temperatures for use in intermediate temperature-solid oxide fuel cells. (C) 2009 Elsevier B.V. All rights reserved.