A synthetic strategy to polydimethylsiloxanes and polymethylsiloxanes containing thiol functions as end- or side-groups, respectively, is presented. Such polymers are important starting materials for elastomeric networks and postpolymerization modifications. The synthesis starts either with vinyl end-functionalized polydimethylsiloxanes or with polymethylvinylsiloxanes. The vinyl groups are reacted either with thioacetic acid or with a thioacetic acid/butanethiol mixture via a UV-initiated thiol-ene reaction to form the respective thioester quantitatively within few minutes. The thioesters are subsequently deprotected to the respective thiols by reduction with LiAlH4. The resulting thiol containing polysiloxanes can be used for the formation of networks or another functionalization. (C) 2016 Wiley Periodicals, Inc.