Nanostructured metal oxides have received increasingly more attention due to their high specific surface area that may increase the active region of the material and hence enhance the performance of many electrochemical devices such as gas sensors or solid oxide fuel cells. However, it is still a major issue to keep these nanostructures stable at the high fabrication and operating temperatures of the electrochemical devices (e.g., solid oxide cells), typically over 1000 degrees C and 700 degrees C, respectively. In this work, thermally stable Ce0.8Sm0.2O1.9 mesoporous scaffolds were infiltrated with a Sm0.5Sr0.5CoO3-delta catalyst, which were then used as electrodes for solid oxide cells. The electrochemical properties of these nanocomposite electrodes in a symmetrical cell at 500-750 degrees C were evaluated using electrochemical impedance spectroscopy. When tested at 700 degrees C for a long period of time, the cells showed no performance degradation but a 50 % reduction in the area specific resistance (ASR = 0.08 Omega center dot cm(2)) after more than 200 h of operation, suggesting that the mesoporous composites are promising electrodes for high-temperature electrochemical devices. (C) 2017 Elsevier Ltd. All rights reserved.