The double perovskites GdBaCo2,Fe(5)06_6 (x = 0, 0.2) and composites (100 y) GdBaCo2,Fe506 _o (X = 0, 0.2) y ceossm0.202 (y = 10-50 wt.%) were investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT SOFCs). Chemical compatibility of GdBaCo2_xFex06_,5 (x = 0, 0.2) with solid electrolyte Ce(0.85)m(0.202), thermal expansion, DC conductivity and electrochemical performance of (100 y) GdBaCo2,Fe(50)6_,5 (x = 0, 0.2) y Ce0.85m(0),202 (y = 10-50 wt.%) were studied. Partial substitution of Fe for Co was shown to lead to decrease of double perovskite GdBaCo2_5Fe505. with the solid electrolyte Ce(08)Sm(0.2)02. Polarization resistance of cathodes studied was found to depend significantly on firing temperature. Variation of solid electrolyte content in (100 y) GdBaCo2_5Fe506_6 (x = 0, 0.2) y Ce0.85m0,202 (y = 10-50 wt.%) composites was shown to allow to optimize their electrochemical performance. Cathode materials of 80 wt.% GdBaCo206_,5 20 wt.% Ce(0,85)m0(20)2 and 65 wt.% GdBaCoisFe(0206),, 3(5) wt.% Ce(0.85)m(02)O(2) were found to have the lowest polarization resistances and reasonable values of thermal expansion coefficient (TEC) and, therefore, can be considered as promising cathode materials for IT-SOFCs. (C) 2013 Elsevier B.V. All rights reserved.