The immobilization or supporting of transition-metal nanoparticles on carriers by different techniques has attracted much attention, considering the significance of nanocatalysts in actual practical applications. Here we report Pd nanoparticles supported on modified porous ?-alumina spheres are adopted as heterogeneous catalysts for the selective hydrogenation of dimethyl terephthalate (DMT) to dimethyl cyclohexane-1,4-dicarboxylate (DMCD), a kind of significant polymer modification and intermediate. ?-alumina spheres as supports were originally modified by in situ growth of magnesium-aluminum layered double hydroxide (MgAl-LDH; also known as hydrotalcite) in the pores and on the surface. Pd nanoparticles were immobilized on the supports by a subsequent wet impregnating method. The resulting Pd nanoparticles catalyst provides quite higher activity/selectivity compared with that supported on the unmodified alumina spheres with the same loading of Pd. The enhanced catalytic performance of the former can be ascribed to the higher dispersion of Pd nanoparticles and the smaller particle size. (C) 2011 American Institute of Chemical Engineers AIChE J, 58: 18531861, 2012