This paper reports the mechanical properties of tubular membranes of mixed conducting La(0.2)Sr(0.8)Fe(0.8)Cr(0.2)O(3-delta) (LSFCO) perovskites at elevated temperatures. Strength, measured in a C-ring test over a temperature range of 22 degrees-1000 degrees C in three different environments - air, 100% N(2), and 90% CO(2)/10% CO mixtures - showed a decreasing behavior with increasing temperature and severity of reducing conditions. A maximum strength value of 340 MPa and a minimum of 105 MPa were observed at room temperature and at 1000 degrees C, respectively, in CO(2)/CO environment. Fractography was used to characterize the flaws and changes in fracture mode. Results indicate that the observed changes in strength and fracture morphology are associated with non-equilibrium segregation of elements when exposed to the reducing environment. (C) 2011 Elsevier B.V. All rights reserved.