A supported Cu(I)@MIL-100(Fe) adsorbent was developed for the separation of CO/N-2 binary gas mixture. The Cu(I)@MIL-100(Fe) was prepared by the wetness impregnation of the divalent copper salts on MIL-100(Fe), followed by the reduction of Cu2+ -> Cu+ under vacuum at elevated temperature. The samples were characterized by N-2 adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The adsorption isotherms of CO and N-2 on Cu(l)@-MIL-100(Fe) were measured by the volumetric method, and the CO/N-2 adsorption selectivities of the samples were calculated based on ideal adsorbed solution theory (IAST). The results showed that (a) the Cu(I)@MIL-100(Fe) adsorbent achieved a superior CO adsorption capacity of 2.78 mmol/g at 298 K and 100 kPa, 7 times of that on parent MIL-100(Fe), and the adsorption behavior was well described by the dual-site Langmuir-Freundlich model; (b) the CO/N-2 adsorption Selectivity of Cu(I)@MIL-100(Fe) was up to 169 at 100 kPa, being 112 times of that of parent MIL-100(Fe); (c) the significant enhancement of CO uptake and CO/N-2 selectivity can be mainly attributed to the selective pi-complexation between CO and Cu(l) on Cu(I)@MIL-100(Fe). (C) 2015 Elsevier B.V. All rights reserved.