Metal–supported　solid　oxide　fuel　cells　(SOFCs)　have　the　merits　of　quick　startup,　low　cost,　and　excellent　robustness,　however,　there　is　a　lack　of　understanding　on　the　effect　of　thermally　driven　elemental　diffusion.　Herein,　we　investigate　the　role　of　elemental　diffusion　on　the　evolution　of　morphologies　and　electrochemical　performance　of　Ni–Fe　alloy　supported　Ni–yttria　stabilized　zirconia　(YSZ)　anode　and　YSZ　electrolyte　film.　The　results　show　that　during　the　co–sintering　process　at　high　temperatures,　there　is　significant　diffusion　of　Fe　element　from　the　Ni–Fe　oxide　substrate　to　the　anode　and　electrolyte.　The　elemental　diffusion　leads　to　the　formation　of　a　NiO　core/NiFe2O4　shell　structure　in　the　anode　and　dissolution　of　Fe　cations　in　the　YSZ　lattices　of　anode　and　electrolyte,　but　also　significantly　enhances　the　sinterability　of　both　layers.　The　negative　effect　of　Fe　diffusion　induced　microstructure　coarsening　is　largely　compensated　by　the　formation　of　an　electrocatalytically　active　Ni–Fe　alloy　in　the　reduced　anode.　The　present　work　provides　insights　into　the　design　and　development　of　efficient　metal–supported　SOFCs　by　taking　advantage　of　elemental　diffusion.　©　2022　Elsevier　B.V.