Abstract Inhibiting Cr 2 O 3 growth and Cr evaporation from metallic interconnects is essential for the long-term performance stability of solid oxide fuel cell (SOFC) stacks. (Mn,Co) 3 O 4 spinel oxide-based coatings have been considered as the most promising coating material for protective coating of metallic interconnects. In this study, we developed a new composition of (Mn,Co) 3 O 4 spinel oxides with reactive elements and Cu dopants: La 0.1 Cu 0.2 Mn 1.35 Co 1.35 O 4 (LCMC) and Ce 0.1 Cu 0.2 Mn 1.35 Co 1.35 O 4 (CCMC). As a result of partial incorporation of reactive elements into the (Mn,Co) 3 O 4 lattice, the secondary phases containing the reactive element dopants were generated and the resulting reactive element-rich clusters were found in the coating layer. Area specific resistance (ASR) measurements of coated interconnect samples at SOFC operating temperatures showed that the LCMC-coated interconnect sample exhibits exceptional stability at 800 °C (ASR increase of ~ 1 mΩ∙cm 2 /kh), whereas CCMC, Mn 1.5 Co 1.5 O 4 (MC), and Cu 0.2 Mn 1.4 Co 1.4 O 4 (CMC)-coated interconnect samples exhibited similar degradation behaviors. The post-reaction structural and chemical analyses showed that LCMC can significantly suppress Cr diffusion, compared to CCMC, MC, and CMC-coated interconnect samples. Based on these results, it is concluded that LCMC is a promising candidate for the protective coating of SOFC metallic interconnects.