Embrittlement of Zircaloy fuel cladding tubes by corrosion media was studied from the viewpoint of its applicability to spent-fuel reprocessing. The results from irradiated as well as unirradiated tubes are summarized as follows: 1.When iodine was employed as the solute, the use of methanol as the solvent caused significant embrittlement of the Zircaloy. 2.For the iodine-methanol solution, the embrittlement increased with the iodine content but saturated at 1 wt%. 3.A water content of up to 10 vol% in the iodine-methanol solution did not decrease the extent of embrittlement. 4.Fracture was of the grain-boundary type, and a fuel cladding tube irradiated to ∼35 GWd/t showed the same embrittlement behavior as an unirradiated one.