To promote the application of traditional (La0.8Sr0.2)(0.)95MnO3-delta-YSZ (LSM-YSZ) oxygen electrodes to both solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) modes at intermediate temperatures, we select PdO as the catalyst and ZrO2 as the PdO stabilizer to decorate the LSM-YSZ. The high active PdO particles enhance the electro- catalytic activity, and stable ZrO2 can hinder the growth and agglomeration of the PdO particles. PdO and ZrO2 are co-impregnated into the LSM-YSZ to form a nano-structured PdO/ZrO2-LSM-YSZ composite electrode. At 750 degrees C, the obtained cell attains a power density peak of 1.114 W cm(-2) in SOFC mode and shows significant improvement of the cell with LSM-YSZ composite oxygen electrode. As a SOEC, when the water content is 90 vol% AH (absolute humidity) at the hydrogen electrode, the cell exhibits an extraordinary cur- rent density of 2.322 A cm(-2) under applied voltage of 2.0 V at 750 degrees C. Moreover, the cell shows notable long-term stability during water electrolysis. Therefore, this study dem- onstrates that the nano-structured PdO/ZrO2-LSM-YSZ based material as a high active and stable oxygen electrode can greatly promote the application of LSM-YSZ electrode in reversible solid oxide electrolysis cell (RSOCs) field. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.