Electrical properties of the YSZ/Al2O3 composite were measured with use of impedance spectroscopy. Electrical conductivity of the composite decreases with increase in the Al2O3 volume fraction and shows typical percolation behaviour. Decrease in the conductivity around five orders of magnitude occurred when the volume fraction of Al2O3 in the composite exceeds a critical level of 86.1%. The electrical conductivity of the YSZ/Al2O3 interface was examined based on the relaxation frequency analysis and finite element modelling. It was concluded that the YSZ/Al2O3 interface conductivity is higher than that of the YSZ grain boundary but similar to, or lower than that of the YSZ grain. (C) 2010 Elsevier B.V. All rights reserved.