In2O3-Ga2O3/Al2O3 nanocomposite catalysts combined the advantages of good propene selectivity offered by Ga2O3/Al2O3 and high propene conversion provided by In2O3/Al2O3 to yield catalysts with excellent de-NOx activity. A high NO conversion to N-2 of 80% was achieved over the catalyst with 2 wt% In and 8 wt% Ga. This NO conversion was attained even in the presence of 15% O-2 and 10% H2O. The In2O3-Ga2O3/Al2O3 nanocomposite remained active in the presence of SO2. This combination of high activity, hydrothermal stability and sulfur resistance made our nanocomposite catalysts very interesting for applications in the selective catalytic reduction (SCR) of NOx. (C) 2009 Elsevier Ltd. All rights reserved.