The effect of nickel oxide addition on the densification behaviour and electrical conductivity of BaCe0.9Y0.1O3-alpha (BCY10) is investigated. Small addition (4 mol%) of this sintering aid reduces the sintering temperature by 200 degrees C and promotes the densification. 95% of the theoretical density was reached after sintering at 1250 degrees C for 10 h in air. Addition of NiO has no detrimental effect on the total conductivity of BCY10 in wet hydrogen. Nevertheless, the activation energy of the recorded blocking effect is higher than that of the bulk contribution, indicating different electrical properties between grains and internal interfaces in pure and NiO doped BCY10. (c) 2009 Elsevier B.V. All rights reserved.