[en] Here we report the sorption behaviors of IO₃^- species on the several sorbents involving activated carbon, CeO₂-modified activated carbon, Ag-attached zeolite, titanate attached activated carbon, and MgO. In addition, the solidification of IO₃^- with alkaline-activated metakaolin (AAMK), so-called geopolymer, were studied. We measured distribution coefficients by the sorbents, leaching behavior from the I doped AAMK into a distilled water and into a sea water. We analyzed chemical species of IO₃^- in sorbents and AAMK by XANES using synchrotron X-ray, and position of I and chemical components present with I in the sorbents and AAMK were analyzed by SEM. Sorption of IO₃^- showed that high distribution coefficients could be obtained in acid solution for activated carbon, CeO₂-modified activated carbon, Ag-attached zeolite, and titanic acids attached activated carbon, and in alkaline solution for MgO. XANES analysis showed that the sorbed I was present as IO₃^-. SEM analysis dis not detect I within the sorbents. These results indicate that IO₃^- is associated by sorbents with outer sphere complexes. Almost all IO₃^- was solidified with AAMK. The leaching test showed that less than 1% of I in AAMK were released into distilled water and into sea water. The XANES spectrum of I in AAMK was nearly the same as that of the KIO₃ standard, indicating that I is present as IO₃^- ion in AAMK. These results indicate that I as the chemical species of IO₃^- is well recovered by the sorbents in acid solution, and is also well solidified in AAMK.