Three different sorbent materials (Ti-, Si-, and Ca-based) were compared for their mercury (Hg-0) capture efficiencies in an entrained flow reactor Agglomerated particles with a high specific surface area were generated h situ by injecting gas-phase sorbent precursors into a high-temperature furnace reactor. Titania particles in the presence of UV irradiation were most effective at mercury capture ( > 98%). In situ generated CaO particles had a capture efficiency of 33% ( without any UV irradiation), while SiO2 was completely ineffective at Hg-0 capture. The efficiency of elemental Hg capture of both CaO and TiO2 particles decreased with increasing SO2 concentration. The increase in the feed rate of the Ti sorbent resulted in the recovery of the higher HgO capture efficiency due to the availability of more active sites. The in situ generated titania sorbents were also effective at HgO capture (> 87%) at elevated temperatures (160 degreesC).