Ring-opening metathesis polymerization (ROMP) of an ethyl-substituted tetracyclododecene (8-ethyltetracyclo[4.4.0.1 2,5 .1 7,10] dodec-3-ene, Et-TCD) was carried out in the presence of a ternary catalyst system consisting of WCl 6 , triisobutyl aluminium (iso-Bu 3 Al), and ethanol. The optimal molar ratio of Et-TCD/WCl 3 / iso-Bu 3 Al/ethanol was found as 500/1/3/2 at which the yield of ring-opened polymer was 100%. 1-Hexene was shown to be an effective molecular weight controlling agent for ROMP reaction of Et-TCD. The hydrogenation of the ring opened polymer (p-Et-TCD) was conducted successfully using Pd(5 wt %)/γ-Al 2 O 3 at 80 o C for 1 h. Chemical structures of p-Et-TCD and its hydrogenated product(H 2 -p-Et-TCD) were characterized using 2D NMR techniques ( H- 13C HSQC). The changes of physical properties such as thermal stability, glass transition temperature and light transmittance after the hydrogenation were also investigated using TGA, DSC, and UV.