A calcium carbonate (CaCO3) sorbent synthesized in the presence of surface modifiers has recently been developed in this laboratory for the purpose of enhancing the reactivity toward SO2 at high temperatures (800-1150 degrees C). The calcium carbonate particles are produced by precipitation from an aqueous suspension of calcium hydroxide by bubbling pure CO2. The operating parameters such as suspension concentration, gas flow rate, and concentration of surface modifiers are varied to study their influence on the particle size, surface area, and pore volume. The synthesized CaCO3 particles exhibit dramatically high SO2 reactivity and sorbent utilization. The increased reactivity is primarily due to the development of an open initial pore structure of the sorbent brought about by the action of surface-active agents, compared to the conventional calcium-based sorbents. zeta-potential measurements indicate that addition and subsequent adsorption of anionic surfactants neutralize the high positive surface charge (30 mV) on the precipitated calcium carbonate and facilitate particle agglomeration and pore structure development. High surface area (>55 m(2)/g) and pore volume (>0.175 cm(3)/g) are obtained for particles with neutral or near-neutral surface changes.