With the goal of improving the electrochemical performance while maintaining good phase stability, the Fe-substituted swedenborgite-type Y0.9In0.1BaCo3Zn1 (-) (x)nFe(x)O(7) (+) (delta) series of oxides have been investigated as cathode materials for solid oxide fuel cells (SOFCs). All the samples with 0 <= x <= 0.8 were obtained as single-phase oxides with the P31c space group. Both the x = 0 and 0.2 samples were stable after 120 h exposure to 600, 700, and 800 degrees C, while the x = 0.6 and 0.8 samples showed instability at 700 and 800 degrees C. The x = 0.4 sample was stable at 600 and 800 degrees C, but generated a BaCoO3 impurity phase at 700 degrees C. The reversible oxygen absorption tendency of these materials was found to increase with increasing Fe content. Increasing the Fe content in the range of 0 <= x <= 0.4 was found to reduce the polarization resistance in the Y0.3In0.1BaCo3Zn1 (-) xFexO7 (+) (delta) + Gd0.2Ce0.8O1.9 composite cathodes, and the x = 0.4 sample was found to have performance superior to that of the well-studied Ba0.5Sr0.5Co0.8Fe0.2O3 (-) (delta) (BSCF) cathode in the range of 400-700 degrees C, making it an attractive cathode candidate for intermediate temperature SOFCs. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.