The gas phase selective hydrogenation of 1,3-butadiene was studied over Pd and Pd-Sn supported on mixed phase theta/alpha-(MA) and pure alpha-alumina (AA). The catalysts were characterized by XRD, XPS, TEM, and FTIR spectroscopy of adsorbed CO. A remarkable improvement in terms of activity and selectivity in the selective hydrogenation of 1,3-butadiene was achieved over Pd-Sn on the mixed phase alumina support in which butane formation and isomerization of 1-butene were suppressed. Nevertheless, Pd-Sn/AA showed much lower activity than Pd-Sn/MA due to lower metal dispersion. (C) 2010 Elsevier B.V. All rights reserved.