A degraded sample of the solid oxide fuel cell cathode material La0.58Sr0.4Co0.2Fe0.8O3-delta (LSCF) is investigated by analytical transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS). In the present study TEM is applied in order to analyse the relevant surface-near regions of an LSCF sample which was pre-treated for 1000 h in a dry O-2-Ar atmosphere and an additional 1000 h in a humidified atmosphere in the vicinity of a silicon source. The results show that Si contamination occurs in an approximately 20 nm thick layer (with local variations from 4 to 35 nm) at the surface of the degraded LSCF sample. In addition, TEM gives evidence of isolated nanocrystals of SrSO4 with diameters in the range of 200-500 nm. A local decomposition of the perovskite phase is found within depths of 500-600 nm from the surface. The decomposition products are ternary oxides which contain either Sr-La-O or Co-Fe-O. (c) 2012 Elsevier B.V. All rights reserved.