Co-doped La0.8Sr0.2Ga0.8Mg0.2O3 (LSGMC) thin films were deposited on Pt(200) substrates by pulsed laser deposition, and the crystal phases and microstructure properties of the films were examined using X-ray diffraction and scanning electron microscope. Depending on the deposition conditions of substrate temperature and oxygen partial pressure, the LSGMC thin films exhibited different phases and microstructures. Especially, the oxygen partial pressure strongly influenced the formation of secondary phases. The single phase of the LSGMC thin film with high density and no cracks was obtained at the optimum condition of substrate temperature of 750 degrees C and at the oxygen pressure of 150 mTorr. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3479543] All rights reserved.