The effect of SO2 on the phase structure, microstructure and the oxygen permeation of a K2NiF4-type membrane based on (Pr0.9La0.1)(2)(Ni-0.74Cu0.21Ga0.05)O4+delta (PLNCG) are investigated. The phase structures of the PLNCG powder samples exposed to SO2-containing atmosphere for different exposure time with different SO2 concentrations at different temperatures are characterized by XRD. The SO2 erosion on the oxygen permeation flux through PLNCG hollow fiber membrane and its recovery are also studied. After the SO2 treatment, the microstructure and phase structure of the spent PLNCG hollow fiber membrane are characterized by SEM, EDS and XRD. The spent membrane shows a porous structure on the sweep side which is rich in sulfur. K2NiF4-structure of the PLNCG membrane has been destroyed by SO2 and Pr2O2SO4. La2O2SO4, NiO are formed in the spent membrane, which indicate PLNCG is sensitive to SO2. (C) 2012 Elsevier B.V. All rights reserved.