The structure-property relationship of Fe-doped SrCoO3-δ was studied. With increase of Fe content in SrCol-xFexO3-δ from x=0 to x=0.2, the phase composition changed pro- gressively in the order of hexagonal→brownmillerite （main）＋hexagonal→cubic （main）＋ brownmillerite→single cubic phase. Transition between the hexagonal/brownmillerite phase and the cubic phase took place with variation of the operating conditions, and was associated with remarkable changes in the electrical conductivity and oxygen permeation flux.
