Palladium catalysts supported on polymers, such as poly(N-vinyl-2-pyrrolidone) (PVP), polyacrylamide (PAA), modified poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and polysulfone (PSF), were used to catalyze the carbonylation of allyl halides to form butenoic acid under mild conditions (40 degrees C, 0.1 MPa). These polymer-supported palladium catalysts exhibit very high activity and stability towards the carbonylation of allyl halides. The turnover frequencies (TOF, mol CO/mol Pd min(-1)) of PVP-Pd are up to 21 and 40 for the carbonylation of allylchloride and allylbromide, respectively, in two-phase (aqueous NaOH-benzene) medium. After repeated use, the turnover (mel CO/mol Pd) of phosphinated PPO-Pd in the carbonylation of allylbromide can be up to 30,000. The effects of solvent, phase transfer agent and the functional support group on the activity of these catalysts were investigated.