The catalytic behavior of palladium supported on polyamides having a pyridine moiety has been studied in the liquid phase hydrogenation of alkadienes and alkynes at 258C and 1 atm pressure. The palladium centre was introduced into the polyamides of formula Ε½ . with n s 2 and 6, by ligand exchange using PdCl PhCN . The resulting precursor catalysts, which were activated in an 2 2 hydrogen atmosphere, selectively reduced alkadienes and alkynes to monoenes and alkenes, respectively. The reaction stopped after 1 molar equivalent of hydrogen had been consumed. The effects of solvent polarity and of support structure has also been investigated. Several techniques have been used to characterize these palladium catalytic systems. The type of interaction between palladium and pyridine modified polyamides was studied by using low molecular weight model Ε½ . Ε½ . compound and IR spectroscopy. X-ray photoelectron spectroscopy XPS and temperature-programmed desorption TPD were used to characterize the palladium catalysts before and after use. It can be concluded from these results that both matrix functional groups i.e. N and O act as coordination sites for the palladium centre and mixed valence state species are py C 5 O formed, giving a selective palladium catalyst. Evaluation of the stability of the supported palladium catalyst was tested in eleven successive runs involving 4300 catalytic cycles: neither loss of activity nor selectivity was found. q 1998 Elsevier Science B.V.