The grain structure and the electrical conductivity of a Y-doped BaZrO3 perovskite type proton conductor were investigated in terms of preparation method. Powders of Y-doped BaZrO3 were prepared using two methods and were sintered at various temperatures and durations. In this study, grain structures showed no effect in regard to the two preparation methods. The samples which were sintered for a relatively long period showed broad grain diameter distributions (GDD). It was also revealed that most of grain boundaries were assigned as random and this trend was not affected by sintering condition. The bulk and grain boundary conductivities of the sample sintered for long period were significantly lower than those of other samples by more than three orders of magnitude. However, this was not related to differences of grain structure and gain boundary characteristics. (c) 2006 Elsevier BX All rights reserved.