In this work, the degradation in output power of a stack with flat-tube anode-supported cells based on double-sided cathodes and its mechanism are studied. After 102 thermal cycles, the OCV keeps about 1.1 V and remains stable, showing that the one-cell stack exhibits a good sealing performance. During the first 100 thermal cycles, when the tem- perature ranges from 750 to 200 degrees C with a heating/cooling rate of 3 degrees Cmin(-1), the stack degradation mainly occurs during the first 34 thermal cycles, and the degradation rate is similar to 0.89%/cycle. During the 101th and 102nd thermal cycles, an additional loading force is applied on the cathode side of the stack at room temperature, and the results shows that the output power at 750 degrees C increases and finally exceeds the initial output. As a result, the primary cause for degradation induced by thermal cycling is believed to originate from the weak interface between the cathode and the interconnect, resulting in an increase in ohmic resistance. The stack degradation can therefore be recovered by a secondary loading force on the cathode side. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.