The influence of indium addition on the catalytic properties of palladium catalysts supported on Al2O3 in the reaction of nitrates reduction to nitrogen was studied. It was found that indium did not show any activity by itself, but acted as a "promoter" for the catalytic activity of monometallic Pd/Al2O3 catalysts. The X-ray diffraction (XRD) and Time-of-flight secondary ion mass spectrometry (ToF-SIMS) studies proved the existence of intermetallic interactions between Pd and In, which probably modified activity and selectivity of bimetallic catalysts in this reaction. The ToF-SIMS technique showed the presence of intermetallic compounds in all the studied bimetallic systems, which could not be proved by XRD measurements in the case of the systems with a small amount of indium. (c) 2008 Elsevier B.V. All rights reserved.