The CO2 capture for a kind of magnesium-based sorbent from commercially available magnesium-based materials was carried out for CO2 capture under high pressures (up to 2.5 MPa) and moderate temperatures (200-400 degrees C). Simultaneously, the evolutions of its physicochemical structures during cyclic capture were analyzed by an X-ray Diffractometer (XRD), a thermo-gravimetric analyzer (TGA), a scanning electron microscope coupled with an electron detection scanning (SEM/EDS), and a surface area and pore structure analyzer. For this sorbent with an unique active component of Mg(OH)(2), its active components from the pure Mg(OH)(2) compound and the initial calcination and followed hydroxylation of magnesium-based materials were carbonated to respectively produce crystalline and amorphous MgCO3 during CO2 capture. The hydroxylation importantly altered relatively small pores into relatively large pores in the sorbent, and the hydroxylation step was necessary, favorable and critical for a higher CO2 capture capacity of the sorbent. Although H2S in the feed gas could cause an important decreasing in its CO2 capture capacity, it hardly affected its cyclic stability. As a whole, the prepared sorbent was suitable for the CO2 removal regardless of H2S presence under high pressures and moderate temperatures. (C) 2015 Elsevier Ltd. All rights reserved.