A commercial activated carbon was functionally modified by silylation with 3-aminopropyltriethoxysilane (APTES). The silylation led to the fixation of weakly basic functional groups, -NH 2 , on the surface as indicated by pH titration, Boehm titration, N 2 − BET analysis and X-ray photoelectron spectroscopic (XPS) analysis. Despite reducing the specific BET area and the pore volume, silylation improved the H 2 S removal capacity so that APTES modified activated carbon (APTES-AC) was 3.55 times more effective than the original activated carbon. XPS results indicate that H 2 S removal may be associated with the amino (-NH 2 ) group and the presence of sulfur in the four oxidation states S 2− , S 0 , S 4+ and S 6+ . The effects of moisture, oxygen content and temperature on the performance of APTES-AC for H 2 S removal were investigated. The presence of moisture in the gas stream was found to have an adverse effect on the H 2 S removal, whilst the presence of oxygen favored the removal of H 2 S by APTES-AC. The higher removal capacity of APTES-AC relative to the original activated carbon indicates that APTES-AC is a potential candidate for the removal of H 2 S from gas streams. The H 2 S removal efficiency of APTES-AC was proved be superior to that of Na 2 CO 3 -impregnated AC by the pilot-scale test of purification H 2 S containing industrial waste gas, yellow phosphorus off-gas.