In this work, in-situ fabricated nano-socketed Fe-Ni particles structured Sr2Fe1.5Mo0.05O6-delta (SFM) electrodes are proposed to simultaneously combine good electrochemical properties of Ni-based materials and good stabilities of SFM-based materials. Preliminary studies on the Ellingham diagram and density functional theory offer certain theoretical basis for realizing the feasibility to extract Fe-Ni alloy from parent Sr2Fe1.3Ni0.2Mo0.5O6.(delta) in the viewpoint of thermodynamic and minimum energy principle. Experimental results according to X-ray diffraction, scanning electron microscopy-elements mapping, high resolution transmission electron microscopy measurements show that a large amount of uniformly dispersed Fe-Ni nano-catalysts are elegantly exsolved from the perovskite oxide parent. Electrical conductivity relaxation results indicate that surface exchange coefficient of SFM-based material is enhanced from 0.5 x 10(-3) to 1.7 x 10(-3) cms(-1) by the in-situ growth of Fe-Ni alloy at 800 degrees C. The in -situ fabricated Fe-Ni@SFM combined with Ce0.8Sm0.2O1.9 (SDC) composite electrodes perform a considerably high electrolysis current density of 1257 mA cm(-2) at 1.3 V, 850 degrees C and polarization resistance of 0.20 Omega cm(2) at open circuit voltage and 850 degrees C. Distribution relaxation of time analysis of impedance spectra shows that the gas conversion process is the rate-limiting step in the Fe-Ni@SFM-SDC hydrogen electrode for steam electrolysis.