Commercial LSM/YSZ cells infiltrated with a solution containing salts with strontium and iron cations in a 1:2 ratio were evaluated for their performance and long term stability under high steam, high current and high temperature. Sr-Fe-O-infiltrated cells showed higher performance and lower degradation than the uninfiltrated LSM/YSZ baseline cell, which demonstrates that appropriate nanomaterial infiltration could improve the performance and mitigate the degradation of solid oxide fuel cells under high steam. The degradation rate of an uninfiltrated LSM/YSZ cell was about 5.98% per 1000h including initial voltage drop after 10% steam. The degradation rate of Sr-Fe-O infiltrated LSM/YSZ cell was 2.05% per 1000h. TEM analysis indicated significant reaction between the infiltrated elements and LSM backbone when infiltrating LSM/YSZ cells. EDS analysis showed La-Sr-Mn-Fe-O-containing nanoparticles formed in the pore on both the LSM and YSZ surfaces. After 2500h operation under 10% steam, the Sr-Fe-O infiltrated cell had a more open porous structure with a modified surface structure and composition. TEM and EDS analysis of the infiltrated cell showed (MnFe)O_x particles formed with a size of ~100nm. 10-50 nm Fe-doped LSM particles were still be observed on YSZ grain surface and on the surface of LSM grain, and iron further diffused into the LSM backbone. Nano-voids were also observed in the interior of LSM grains for the cell operated under 800°C, 0.75A/cm² and 10% steam for 2500h. The performance data and TEM analysis indicate that infiltration can be used to boost cell performance while also decreasing long term degradation by changing the degradation modes present in the cathode.