Process for the preparation of functionalized polymers

A process for the preparation of a functionalized polymer comprising reacting a polymer of a conjugated diene hydrocarbon or copolymer of a conjugated diene hydrocarbon and a vinyl aromatic compound, at least part of said polymer or copolymer being formed by 1,2-polymerization of the conjugated diene hydrocarbon, with (a) carbon monoxide and (b) water and/or an alcohol, in the presence of a catalytic system prepared by combining (i) a salt of divalent palladium, (ii) a phosphine ligand which has the general formula A ##STR4## in which R.sup.1, R.sup.2 and R.sup.3 each represent an optionally substituted aryl group and (iii) an acid, except hydrohalogenic acids, wherein the acid has a non-co-cordinating anion and a pk.sub.a below 2, measured at 18.degree. C. in aqueous solution, and is not a carboxylic acid.