SrO-doped CeO2 electrolyte has been evaluated in single-cell configuration under solid-oxide fuel cell operating conditions. Because of oxygen loss from the crystal lattice, the material experiences a macroscopic expansion of several percent at 1000 degreesC, On extended cell operation, strontium precipitates-out at/near the anode, resulting in irreversible cell degradation in the case of SrO-doped CeO2. Precipitation and diffusion of SrO causes decreased ionic conductivity and may result in anode delamination, SrO precipitation is attributed to insolubility of the dopant in the reduced CeO2 phase. The diffusion of strontium seems to be related to the flux of oxygen through the sample, but an exact mechanism is unknown.