Ring-opening metathesis polymerization (ROMP) of a polycyclic olefin monomer (tetracyclododecene, TCD) was carried out using various catalyst systems. The catalysts included titanium-based ternary system (titanium tetrachloride, TiCl4/triethylaluminum, Et3Al/triethylamine, Et3N), tungsten-based ternary system (tungsten hexachloride, WCl6/triisobutyl aluminum, (i-Bu)(3)Al/ethaool), and a ruthenium benzylidene catalyst (Grubbs 1st catalyst). The Grubbs 1st catalyst was most active in ROMP of TCD. The tungsten-based catalyst was found to be more active than the titanium-based catalyst. In contrast to the titanium-based and the Grubbs 1st catalysts, ROMP of TCD with the tungsten-based catalyst was very sensitive to gelation in the course of reaction. The effects of ethanol, WCl6 concentration, TCD/WCl6 ratio, and I-hexane on the polymerization yield and the polymer gel formation were investigated in detail, and optimized ROMP conditions were determined. Chemical structure of synthesized polymer was characterized using one- and two-dimensional 150 MHz C-13 and 600 MHz H-1 nuclear magnetic resonance spectroscopy, molecular weights were measured using gel-permeation chromatography, and thermal properties were characterized using differential scanning calorimetry. Number-average molecular weights (M-n) of the polymer were in the range of 1.5-4.7 x 10(4) g/mol, and glass transition temperatures were in the range of 185-220 degrees C. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 479-485, 2010