Investigative results of Y concentration dependence of total conductivity, and testing results of self-supported cells, gave us knowledge to realize intermediate temperature operating SOFCs using Y-doped BaZrO3 proton conductors. An increase of Y concentration improved electrical properties of grain boundaries drastically. As a result, total conductivity of a 15mol% Y doped BaZiO3 sample in wet air and wet Ar showed 5mScm-1 at 400°C The performance of the self-supported cells was very low because of high electrolyte resistance caused by those thicknesses. Open circuit voltage (OCV) was over IV in the temperature range of 600°C to 400°C in spite of low ionic transparent number in wet air at 600°C Degradation of electrolytes was not observed during tests. From those results, electrode-supported cells using Y-doped BaZrO3 will show sufficient cell performance for intermediate temperature SOFCs.