Graphene carboxylic acid based polynorbornene nanocomposites were fabricated following simple synthetic protocol with different graphene loading. Polynorbornene (PNDA) was functionalized with hexamethylene diamine modified graphene carboxylic acid (HXNG) to form new hybrids: PNDHXNG1-3. Formation of monomer (NDA) and PNDA were confirmed by standard analytical techniques. Covalent attachment between PNDA and HXNG was confirmed by IR, Raman and PXRD. Hybrids exhibited excellent solubility in DCM:MeOH (2:1). Increased thermal stability and enhanced value of T-g of the hybrids, as compared to PNDA was evidenced from TGA, DTG, DTA and DMTA analysis. 69% increment in storage modulus was achieved in case of PNDHXNG3. Almost 97%, 73% and 181% increment were observed in yield stress, stress at break and Young's modulus respectively in case of PNDHXNG3. Improved thermal and mechanical properties were observed with increasing HXNG loading in PNDHXNG1-3. Morphological studies revealed excellent miscibility between HXNG and PNDA in PNDHXNGs owing to improved thermal and mechanical properties. (C) 2017 Elsevier Ltd. All rights reserved.