Doubly functionalized polar norbornenes 3a-3g substituted by both a variety of ester and cyano groups were polymerized by ring-opening metathesis polymerization (ROMP) with a Ru carbene complex 2 bearing 3-bromopyridine as a ligand (third generation Grubbs' catalyst) in a living manner. The successive hydrogenation of the main-chain double bond in the synthesized living ROMP polymers 4a-4g with a hydridoruthenium complex was exploited. The comparison of thermal properties of a series of ring-opening metathesis polymers 4a-4g with those of their hydrogenated derivatives 5a-5g revealed the decrease of glass transition temperatures (T-g) but little change of the 5% decomposition temperature (T-d(5)). In all cases examined in this study, a decrease of T-g by hydrogenation was around 20-40 degrees C, regardless of the ester substitutents. In the presence of the additional PCy3, triethylamine, and methanol after complete consumption of monomer 3a under the living ROMP condition, the tandem ROMP-hydrogenation of the resulting polymer 4a generated in situ was attained under a H-2 (9.8 MPa) atmosphere at 80 degrees C to afford the hydrogenated polymer 5a, retaining the narrow polydispersity of 1.03. (C) 2008 Wiley Periodicals, Inc.