Modern well-defined ruthenium alkylidene complexes became preferred catalysts for a great variety of metathesis reactions. In this study, an air-stable new ruthenium alkylidene catalyst bearing 3-methoxypyridine has been prepared in one pot at high yields using commercially available [(PCy3)(2)Cl2Ru=CHPh] catalyst. Ruthenium based complex, (PCy3)(3-MeOPy)(2)(Cl)(2)Ru=CHPh, was characterized by a H-1 NMR doublet at 20.00 (J=11.9 Hz) for the Ru=CH proton. The catalyst was tested in model ROMP reactions and found to be very effective for ring-opening metathesis polymerization (ROMP). The optimal conditions for the polymerization of exo-N-benzylnorbornene-5,6-dicarboximide using the newly synthesized catalytic system were determined. (C) 2013 Elsevier B.V. All rights reserved.