Thiol- and amino-functionalized SBA-15 silicas with uniform mesoporosities were prepared and employed for removing heavy metal ions from waste water; the thiolated SBA-15 adsorbent exhibited a higher complexation affinity for Hg2+, while the other metal ions (Cu2+, Zn2+, Cr3+ and Ni2+) showed exceptional binding ability with its aminated analogue.