A polymer-supported Pd(II) species has been prepared by means of an oxidative addition reaction between Pd(PPh3)4 and chloromethylated crosslinked polystyrene. This catalyst has been used for the hydrogenation of alkenes and alkynes under mild conditions. Quantitative studies on the rates of hydrogenation of selected substrates are reported with the mechanisms being discussed. Data on the high recycling efficiency of the catalyst as well as solvent effects on the reaction are presented. Comparisons of the catalyst with earlier reported Pd(II) species supported on polystyrene have been made. © 1985.