Oxygen permeation through dense ceramic membranes of the SrCo0.85Ti0.15O3-delta cubic perovskite solid solution was studied in the range of the membrane feed-side oxygen partial pressures (p(2)) 0.21 to 100 atm at temperatures of 850-1040 K. The dependence of the oxygen fluxes on membrane thickness suggests that bulk ionic conductivity is the permeation-determining factor at high oxygen pressures (p(2) > 1 atm). Increasing the oxygen pressure up to 80-100 atm was found to result in a drastic increase of the permeation flux, accompanied by a partial decomposition of the cubic perovskite phase of SrCo0.85Ti0.15O3-delta, forming two isostructural perovskite-type phases. No phase changes were observed after testing ceramics in the oxygen pressure range of 1-60 atm. The high oxygen permeation fluxes obtained demonstrate the applicability of SrCo0.85Ti0.15O3-delta membranes at high oxygen pressures. (C) 2000 Elsevier Science Ltd.