The perovskite ceramic BaCe0.2Zr0.7Y0.1O3- (BCZY27) with a small addition of NiO has previously been shown to densify at a reasonable sintering temperature while maintaining high protonic conductivity. However, some questions remain regarding the role, location, and resulting phase of the NiO addition. Transmission electron microscopy and atom probe tomography (APT) were used to analyze BCZY27 specimens before and after use as a hydrogen separation membrane. The effects of electrolyte operation on the local chemistry were explored. Grain boundaries were specifically targeted due to their higher energies and importance for overall conductivity. The compositions measured by APT were found to be dependent on the laser energy used for analysis, but conditions were found which gave results reasonably consistent with x-ray fluorescence results. Specimens before and after electrolytic use showed no measureable difference in the local chemistry. Most grain boundaries exhibited little compositional variation from the bulk material, with only a slight increase in yttrium being apparent. A few grain boundaries had particles 2-15nm in diameter, which were found by APT to be NiO.