Proton conducting oxides are promising electrolyte materials for intermediate temperature solid oxide fuel cells (SOFCs). Among the oxide proton conductors, Y-doped BaZrO3 offers a combination of high conductivity and good chemical stability. However, low conductivity of grain boundaries compared to the grains (bulk) is the main obstacle for using this material as an electrolyte. Consequently, there is a great demand for increasing total conductivity of this material by improving the electrical properties of grain boundaries. In this respect, we studied the effect of high-temperature annealing and the segregation behavior of two different trivalent dopant cations (Sc3+ and Zr4+) on the grain boundary properties. This project is in collaboration with the Department Maier (Max Planck Institute for Solid State Research).