The surface of ordered mesoporous (MCM-48) silica has been subjected to covalent grafting with silane molecules containing one to three amino groups. The dielectric properties of the materials were studied in detail, and the functionalized materials were used for CO2 adsorption at room temperature, followed by regeneration under either conventional heating or microwave irradiation. It has been found that, as the intensity of functionalization with amino groups increases (from mono- to tri-amino silanes) both the CO2 load and the dielectric response at microwave frequencies increase. In particular, functionalization with a tri-amino silane derivative gave the highest CO2 adsorption and the fastest microwave heating, resulting in a fourfold acceleration of adsorbent regeneration. The grafted material was fully stable for at least 20 adsorption-regeneration cycles, making it an ideal candidate for microwave-swing adsorption (MWSA) processes. (c) 2015 American Institute of Chemical Engineers AIChE J, 62: 547-555, 2016