Due to the "click" chemistry characteristics of the thiol-ene reaction, these transformations have been gaining an increasing amount of attention in current chemical research. The high efficiency and selectivity of these transformations have been useful for many areas of study, from small molecule organic synthesis, to polymer synthesis and functionalization, to bio-conjugation reactions. In this work, a study of a novel method of photochemical thiol-ene reactions using alkyl halides and an tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)(3)) photocatalyst is investigated. This process is shown to progress rapidly and has the benefit of low catalyst and initiator concentrations relative to reagents as well as mild conditions associated with photochemical processes. To understand the mechanism of this process, catalyst and initiator concentrations and other reaction conditions are varied. To demonstrate the utility of this process, a step-growth thiol-ene polymer is synthesized using dithiol and diene monomers and a crosslinked polymer network is synthesized as well. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1931-1937