NOVELTY - Material comprises: a first metal oxide (I) having a perovskite crystal structure; a second metal oxide having an electronic conductivity which is greater than an electrical conductivity of the first metal oxide, a thermal expansion coefficient which is less than a thermal expansion coefficient of the first metal oxide, and a perovskite crystal structure; and a third metal oxide having a fluorite crystal structure.    USE - The material is useful in a cathode of solid oxide fuel cell (all claimed).    ADVANTAGE - The material: increases ionic resistance and exhibits excellent durability for the cell; reduces cathode resistance; and utilizes perovskite material that maintains desirable low-temperature resistance characteristics, provides relatively high ionic conductivity at a relatively low temperature, thus stability of cell is improved by minimizing the interlayer thermal mismatch of the cell.    DETAILED DESCRIPTION - Material comprises: a first metal oxide of formula (BaaSrbCoxFeyZ1-x-yO3-~d) (I) having a perovskite crystal structure; a second metal oxide having an electronic conductivity which is greater than an electrical conductivity of the first metal oxide, a thermal expansion coefficient which is less than a thermal expansion coefficient of the first metal oxide, and a perovskite crystal structure; and a third metal oxide having a fluorite crystal structure.    Z = at least one element of groups 3-12 and a lanthanide element;    a, b = 0.4-0.6;    a+b = less than or equal to 0.1;    x = 0.6-0.9;    y = 0.1-0.4;    x+y = less than 1; and    delta = is selected such that the first metal oxide is electrostatically neutral.    INDEPENDENT CLAIMS are also included for:    (1) a cathode for a solid oxide fuel cell, where the cathode comprises the material; and    (2) the solid oxide fuel cell comprising: the cathode for solid oxide fuel cell comprising the material; anode disposed to face the cathode; and a solid oxide electrolyte disposed between the cathode and the anode.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional view of structure of solid oxide fuel cell.    Solid oxide fuel cell (10)    Solid oxide electrolyte (11)    Cathode (12)    Anode (13)