In this work, the chemical stability of the electrolyte material BaZr0.8Ce0.1Y0.1O3 (BZCY81) is studied in CO2 and CO2-H2. Dense pellets prepared by sintering with NiO as a sintering aid were exposed to up to 10 bar CO2(-H2) for up to 150 h at elevated temperatures (400-800°C). After exposure, the pellet surface was analyzed by grazing incidence X-ray diffraction (XRD), scanning electrode microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to search for BaCO3 formation. Overall, the electrolyte material displayed excellent stability towards CO2. A small increase in apparent BaCO3 concentration on the pellet surface was only detected by XPS for samples aged in CO2 and CO2-H2 at 800 °C. However, BaCO3 was not visible by XRD and SEM-EDS, indicating that the reactivity is limited to a nm-thick region of the electrolyte surface. The impact of processing conditions such as sintering temperature and use of NiO sintering aid on the electrolyte stability will be discussed.