The electrical transport properties of SrFeCo0.5Ox were studied in various oxygen partial pressure (rho(O2)) environments by conductivity experiments. Oxygen stoichiometry was determined by thermogravimetric analysis, while oxygen chemical diffusion coefficient was derived from time relaxation experiments by abruptly changing the rho(O2) in the surrounding atmosphere and monitoring specimen weight change as a function of time. The structure of SrFeCo0.5Ox was determined by X-ray powder diffraction. Conductivity results showed that SrFeCo0.5Ox is a mixed conductor with high combined electronic and oxygen ionic conductivities. At 950 degrees C in air, total electrical conductivity is approximate to 23 S cm(-1) and the ionic transference number is approximate to 0.4. In high-p(O2) environments, interstitial oxide ions and holes are the predominant charge carriers in that the SrFeCo0.5Ox system has an oxygen-deficient perovskite-like layered structure. Its structure can be fit by Rietveld analysis with an orthorhombic unit cell of lattice parameters a=11.112, b=19.12, c=5.528 Angstrom, and cell volume of 1174.67 Angstrom(3).