Pd nanoparticles supported in mesoporous silica SBA-15 (or Pd/SBA-15 nanocomposites) were prepared by ion-exchange with cationic Pd precursor in an alkaline solution on an uncalcined silica. The high Pd loading in these nanocomposites can be achieved up to 5.21 wt.% by adjusting the pH value of the solution. The surface area and the pore volume decrease with increasing Pd loading. The Pd nanoparticles equal to or smaller than 6 nm in size in the nanocomposites are distributed in the channels of the mesoporous SBA-15. The Pd/SBA-15 nanocomposites exhibit excellent catalytic activities and high reuse ability in air for the Heck carbon-carbon coupling reactions. (C) 2011 Elsevier B.V. All rights reserved.