(Y 0.5 In 0.5 )BaCo 4−x Zn x O 7 (1.0 ≤ x ≤ 2.0) oxides crystallizing in a trigonal P31c structure have been explored as alternative cathode materials for solid oxide fuel cells (SOFC). At a given Zn content, the (Y 0.5 In 0.5 )BaCo 4−x Zn x O 7 compositions exhibit superior phase stability compared to YBaCo 4−x Zn x O 7 and InBaCo 4−x Zn x O 7 at the operating temperatures of SOFC (600–800 °C). In the (Y 0.5 In 0.5 )Ba(Co 4−x Zn x )O 7 system, the x = 1 sample offers a combination of good electrochemical performance, low thermal expansion coefficient (TEC), and enhanced chemical stability against Ce 0.8 Gd 0.2 O 1.9 (GDC) electrolyte while demonstrating good phase stability at 600–800 °C for 100 h. Optimum cathode performance could be obtained by employing (Y 0.5 In 0.5 )BaCo 3 ZnO 7 + GDC (50:50 wt.%) composite cathodes attached at 850 °C for 3 h as evidenced by ac-impedance spectroscopy, and the fuel cell performance of this composite cathode was evaluated using anode-supported single cells. With a combination of excellent high-temperature phase stability, low TEC, and good electrochemical performances, the trigonal (Y 0.5 In 0.5 )BaCo 3 ZnO 7 composition is an attractive cathode candidate for intermediate temperature SOFC.