The first examples of unsymmetrical olefin cross-metathesis reactions in water, involving water-insoluble substrates, at room temperature and using commercially available catalysts are reported. The key to success is to include small percentages of the nonionic, vitamin E- based amphiphile “PTS”. The nanometer micelles formed accommodate water-insoluble substrates, along with a readily available Ru-based metathesis catalyst. Reactions ...