One-stage synthesis of cagelike porous polymeric microspheres and their application as catalyst scaffold of Pd nanoparticles are discussed. The synthesis of cagelike porous polymeric microspheres is achieved by W/O/W emulsion polymerization of a surfactant monomer of N-(4-vinylbenzyl)-N, Pd N-dibutylamine hydrochloride and a hydrophobic monomer of styrene in water. Ascribed to the surfactant monomer, convenient one-stage synthesis of cagelike porous polymeric microspheres is afforded, and cagelike porous polymeric microspheres with size ranging from 300 to 600 nm and pore volume as large as 0.31 cm(3)/g are fabricated. The porous character and the inherent quaternary ammonium moieties make the cagelike porous polymeric microspheres to be the promising catalyst scaffold of Pd nanoparticles, and up to 10 wt % Pd catalyst with the metal particle size ranging from 2.1 to 5.7 nm is loaded. The catalytic hydrogenation of nitrobenzene by H-2 demonstrates that the heterogeneous Pd catalyst is efficient and reusable.