Pristine and surface modified multi-walled carbon nanotubes (MWCNT) were used to fabricate MWNTV epoxy composite materials by solution mixing process. A suitable chemical treatment was performed in order to create the functional sites on MWCNTs for firm interlocking in between the filler and the matrix for better interfacial load transfer. The increase in oxygen related moieties was confirmed by x-ray photoelectron spectroscopy. The effect of MWNT addition and their surface modification on the flexural strength and thermal conductivity was investigated. FE-SEM study was carried out for observing the morphology of reinforcing materials as well as its dispersion in the polymer matrix. Thermal conductivity of nanocomposites containing 1wt% of modified and unmodified MWCNT were evaluated. The increase in flexural strength of the composite materials was observed with the addition of pristine and modified MWCNT by 55% and 100 %, respectively.