Background: Ring Opening Metathesis Polymerization (ROMP) can provide a wide range of possibilities for polymers and copolymers synthesis. Norbornene and its derivatives can serve as monomers for the synthesis of highly molecular mass polymers with widely varying structure.Objective: In this paper a new polymers based on dimethyl ether norbornenedicarboxylic acids were prepared by ring-opening metathesis polymerization in the presence of a catalyst of Hoveyda-Grubbs II. Method: The resulting polymers and monomers were characterized by NMR, IR, GCMS, TGA, DSC. Results: Chemical yield of investigated processes was more than 95 %, molecular mass of the obtained polymers was also relatively high (more than 4.5•106 g/mol). The research findings have shown that polymers obtained with bi- and tri-functional comonomers are more heat resistant and are stable up to the 370 °C. Also it was shown that the addition of bi-and tri-functional comonomers facilitates the significant improving of mechanical and physical properties. Polymer obtained with 3 wt.% of tri-functional comonomer possesses the biggest values of modulus of elasticity in flexure, breaking elongation and breaking strength. Conclusion: New polymers based of exo,exo and endo,endo-dimethyl esters of 5-norbornen-2,3-dicarbonic acid (DME) with addition of bi-functional and tri-functional comonomers were synthesized via metathesis polymerization. The addition of 3 wt.% of bi-functional and tri-functional comonomers resulted in polymers having a higher crosslinking degree and glass transition temperature. The synthesized polymers demonstrated a higher application temperature and better mechanical and physical properties than poly-DME.