The potential usage of Copper (Cu) is very limited, where combined mechanical and thermal properties are desirable, which can be overcome by using carbon nanotube (CNT) as a reinforcement. An attempt was made to synthesize Cu/CNT composites by varying CNT diameter and its concentration through a molecular level mixing technique followed by uniaxial compaction and conventional sintering. The sintering behaviour of Cu and Cu/CNT composites was studied to understand the influence of different parameters. The sintering duration of Copper was decreased with an increase of CNT diameter. The maximum enhancement of properties was achieved at 0.25 wt.% CNT irrespective of its diameter, where the thermal conductivity and hardness were obtained as 328 W/mK at 20-40 nm diameter CNT composites and 81.2 +/- 2.9 VHN at 40-60 nm diameter CNT composites, respectively. The conventional method of synthesize can generate the desired characteristics of composites at par with high end techniques, such as SPS. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.