The poly(styrene), PS, of 450 nm diameter, poly(styrene-co-4-vinylphenylboronic acid), PSB, nanoparticles of 220-400 nm diameter, and poly(styrene-co-4-vinylbenzoic acid), PSC, nanoparticles of 240-305 nm. were prepared by emulsifier-free emulsion polymerization. The surface of PS, PSB, and PSC nanoparticles were loaded with Pd nanoparticles by reduction of Pd ions using gamma-irradiation in order to apply catalyst in Sonogashira coupling reaction. The Pd-PS, Pd-PSB and Pd-PSC were characterized by High-Resolution Transmittance Electron Microscopy (HR-TEM), Field-Emission Scanning Electron Microscopy (FE-SEM), and Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), respectively. The HR-TEM, XRD and ICP-AES data show that the Pd nanoparticles were loaded on the surface of PS, PSB, and PSC nanoparticles, respectively. Catalytic efficiency of the Pd-PS, Pd-PSB and Pd-PSC nanoparticles was tested in Sonogashira coupling reaction. The catalytic efficiency of the Pd-PS, Pd-PSB, and Pd-PSC nanoparticles was increased with increasing Pd nanoparticle contents. (C) 2007 Elsevier B.V. All rights reserved.