Solubilization of the hydrophobic Hoveyda-Grubbs' catalyst in micellar aqueous phase has been achieved using dodecyl and cetyl ammonium chloride as surfactants. The domain of solubilization has been estimated before carrying out ring-opening metathesis polymerization in these micellar solutions with a hydrophilic monomer. Kinetics orders have been determined relative to monomer, initiator, and surfactant. A good control of the molecular weight has been obtained for ratios [micelles]/[initiator] over 1. The better control of the polymerization obtained in micellar solution has been explained by a difference of reactivity leading to a more efficient initiation step in the presence of the micelles. (c) 2008 Wiley Periodicals, Inc.