Ring opened metathesis polymerization was carried out on a number of cyclic olefins using Cl-2(PCy3)(2)Ru[CH(Ph)] and [(eta(6)-p-cymene)(PCy3RuCl(=C=C=CPh2)]OTf in dichloromethane and a range of ionic liquids. Microstructural parameters were determined from the C-13 NMR spectra recorded of the polymers. The findings indicate that an increase in activity of both catalysts can occur in certain ionic liquids systems. It was also observed that the activity of [(eta(6)-p-cymene)(PCy3)RuCl(=C=C=CPh2)]OTf increases upon addition of an excess of phenol (C) 2009 Elsevier B.V. All rights reserved.