exo,exo-Norborn-5-ene-2,3-diyl bis(S-methyl dithiocarbonate)(1)and exo,exo-norborn-5-ene-2,3-diyl bis(methyl carbonate) (2) were polymerized by ring-opening metathesis polymerization (ROMP) using Mo(CH-t-Bu)(NAr)(O-t-Bu)2. This is the first time a ROMP of norbornenedixanthate using a molybdenum-carbene initiator was successful. Depending on the bulkiness of the substituents, a higher stereoregularity of the polymer was achieved. Spectroscopic data (IR, NMR) of poly[norborn-5-ene-2,3-diyl bis(S-methyl xanthate) (poly1) show a complete trans connection of the repeating units, whereas the oxa analogue is not as stereoregular. Thermal properties of poly1 offer interesting possibilities for application as a precursor polymer to poly(cyclopentadienylenevinylene) (poly3). By using the sulfur analogue, the temperature of elimination was reduced to 200-degrees-C (maximum of the DSC plot).