The biphasic hydrosilylation of 1-hexadecene with siloxane B9800 in a range of ionic liquids is reported. Of the ionic liquids tested, [C(4)py][BF4] and [C-4-3-pic][BF4] offer the optimum compromise between activity and catalyst retention. Several platinum precatalysts were screened, of which K2PtCl4 and Pt-(PPh3)(4) were found to give the best performance; the former provides the highest activity, while the latter offers higher stability and recyclability, and depending on the conditions, both can afford either homogeneous or soluble nanoparticle catalysts as the active species. A number of reaction parameters were varied, and the effects of oxygen, water, and chloride impurities on the reaction were studied. In addition, since nanoparticle catalysts were observed, various strategies to stabilize nanoparticles were screened, but none of them resulted in a superior catalytic system.