Dioxin removal efficiency of various adsorbents, in a fixed-bed column was examind usinng 1, 2, 3, 4-tetrachlorinated dibenzo-p-dioxin (T4CDD). The adsorbents tested were four kinds of activated charcoal, six kinds of activated carbon, a carbon residue made from vinyl chloride resin, a carbon residue made from building lumber, ten kinds of inorganic adsorbents, two kinds of flyash from two slagging incinerators containing unburned carbon and four kinds of flyash from two waste incinerator containing it. Carbon adsorbents with a pore volume of for pores of 2-50 nm in diameter are more than 0.06 cm(3)/g and BET surface area are more than 260 m(2)/g have similar T4CDD removal efficiencies, which were controlled by mass transfer rate in a boundary film. In contrast, T4CDD removal efficiency of carbon adsorbents with smaller pore volumes and BET surface areas was controlled by mass transfer rate in the pores. Activated clay has the highest T4CDD removal efficiency among the inorganic adsorbents. Diatomaceous silica and slaked lime adsorb little T4CDD. Unburned carbon in the flyash had almost equal T4CDD removal efficiency to activated carbon.