This work focuses on the thermal properties, mechanical behavior and fracture analysis of carboxylic acid (-COOH) modified multi walled carbon nanotubes (MWCNT) reinforced epoxy – CF composites. MWCNT – epoxy nanocomposites were prepared by ultrasonic probe method. The CF composites with Epoxy – MWCNT nanocomposites were prepared by conventional hand lay-up method followed by compression molding. The addition of 1.5 % MWCNT to the epoxy resin significantly enhanced the mechanical properties such as fracture toughness, tensile and flexural properties, while the impact strength decreased. Thermogravimetric analysis showed that the addition of MWCNT in the CF epoxy composite improved the degradation onset temperature while there was a decline in the temperature at which of maximum weight loss occurred. The effect of MWCNT on composite properties were correlated to nanofiller dispersion and interaction with polymer by morphological analysis using field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR) analysis. However, at higher concentration of carbon nanotubes, both thermal and mechanical properties showed slight decline due to the formation of agglomerates.