A single cell for SOFC operating at low temperatures, is provided, including a first solid electrolyte with oxide ion conductivity at 800.degree. C. of 0.015 S/cm or more and bending strength of 600 MPa or more, a fuel electrode and bonded to one side of the first electrolyte, comprised of a cermet of a catalyst and a second solid electrolyte with a conductivity of 0.08 S/cm or more, and an air electrode bonded to the other side of the first electrolyte comprised of a compound of first perovskite type oxide with a third solid electrolyte. The electrodes are coated with fuel and air electrode contact layers, respectively.