A novel Cu@C core-shell microstructure was prepared by reduction of [Cu(NH3)(4)](2+) with glucose using a mild hydrothermal process. The carbon shell of such Cu@C composite can be tuned to different carbonization degrees just through varying the calcination conditions. The structural properties of as-prepared Cu@C were investigated in detail by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron micrographs (TEM) and Raman spectra. In addition, these Cu@C composites were firstly used to catalyze the C-N cross coupling of amines with iodobenzene. Among them, the catalytic ability of Cu@C composites increased as their surface carbon's carburization degree improved. (C) 2015 Elsevier Ltd. All rights reserved.