An acid gas sorbent composition is disclosed. The composition comprises a compound having the following formula: (SiO2)x(OH)y F.B wherein F optionally exists and said F is at least one of the following: a functionalized organosilane, a sulfur-containing organosilane, or an amine-containing organosilane; and wherein B is a hygroscopic solid at a preferred water to solid molar ratio of about 0.1 to about 6, and more particularly, B is a basic inorganic solid including, but not limiting to, alkali or alkali-earth metal oxides, hydroxides, carbonates, or bicarbonates, containing at least one of the following metal cations: calcium, magnesium, strontium, barium, sodium, lithium, potassium, cesium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, dysprosium, scandium, ytterbium, yttrium, or erbium; wherein the molar ratio of y/x is equal to about 0.01 to about 0.5.