Thermally robust chelating adsorbents for the direct capture of vapor phase mercury have been developed. In these adsorbents, chelating ligands are bonded to a mesoporous substrate and coated with an ionizing surface nanolayer. The effectiveness of these adsorbents for capture of oxidized mercury at elevated temperature (160°C) has been demonstrated in fixed-bed experiments; oxidized mercury capacities as high as 58 mg/g adsorbent have been observed. The capacity of the fully functionalized adsorbent is believed to be the sum of the capacities of the ionic coating, uncovered ligands, and covered ligands. Pore size does not have a significant effect on mercury adsorption. Mercury diffusion through the ionic coating layer is believed to be the rate limiting step for mercury capture. The chelating adsorbent technology can also be used to capture elemental mercury at elevated temperature by proper selection of ionic liquid coating; elemental mercury capacities as high as 15.6 mg/g adsorbent were observed for one unoptimized prototype adsorbent, which is quite high compared to the 2-3 mg/g adsorbent obtained using commercially available activated carbon. These results suggest that the simultaneous removal of elemental and oxidized mercury at elevated temperatures is feasible.