Mo2C submicron layer coated diamond particles prepared by a molten salts route with Mo powder as the starting material were used as the filler in Cu- and Al- matrix composites. The microstructure and thermal property of the composites prepared by a vacuum pressure infiltration method were investigated. When introducing a 500nm thick Mo2C layer, the thermal conductivity of the composites with different matrix presented different performance. A high thermal conductivity (657 Wm(-1) K-1) was obtained in diamond/Cu composites owing to the improved interfacial bonding and lower interfacial thermal resistance, while the thermal conductivity of diamond/Al composites decreased from 553 W m(-1) K-1 to 218 Wm(-1) K-1 when introducing the Mo2C layer, which can be attributed to the formation of harmful granule-phase (Al12Mo) at the interface of diamond and aluminum. This work provides a promising approach to improve performance of diamond reinforced metal matrix composites by selecting carbide as an interface modifier. (C) 2017 Elsevier B.V. All rights reserved.