Pd nanoparticles incorporated in a hydrotalcite (HT) host were prepared via anion exchange between a dilute suspension of HT-nitrate and a Pd hydrosol stabilized by the anionic surfactant sodium dodecyl sulfate. Samples of two of the resulting Pd organoclays, Pd-HT1 and Pd-HT2, with metal contents of 0.1 and 0.42%, respectively, were subjected to further investigations. Characterization via ICP-AES, XRD, and TEM measurements indicated the deposition of fairly monodispersed Pd particles, predominantly on the external surface of the HT layers. The Pd-HT samples proved to be efficient catalysts for the liquid-phase sernihydrogenations of both terminal and internal alkynes under mild conditions. For the transformation of phenylacetylene to styrene, a bond selectivity of 100% was obtained, and the cis stereoselectivities for the hydrogenations of the internal alkynes 4-octyne and 1-phenyl-1-pentyne reasonably approached 100%. The catalytic activity of Pd-HT increased with the Pd dispersion, whereas the alkene selectivity remained essentially unaffected. (C) 2003 Elsevier Inc. All rights reserved.