The present invention relates to a procedure in which a functionalized polysiloxane is synthesized in the presence of a platinum catalyst, and halogen-functionalized polysiloxanes obtained according to the procedure. The procedure is defined herein by reacting a) at least one polysiloxane comprising at least one hydrogen atom bonded to a silicon atom; b) at least one heterocyclic compound; and c) at least one halogen-containing compound, wherein the reaction is catalyzed by at least one platinum catalyst. The synthetic pathway is described as a halosilation reaction in which a heterocyclic molecule is ring-opened in the presence of a platinum catalyst and a halogen source, resulting in a formal insertion of the opened heterocycle into the SiH bond. On the final product, the heteroatom of the former heterocycle is bonded to the silicon atom from the former hydrosiloxane moiety while the halogen is bonded to the last carbon atom of the opened chain.