The diffusion behavior of iodine in yttria stabilized zirconia (YSZ) was investigated as a function of the temperature. Iodine implantation was performed in this cubic solid solution by irradiating material samples with 1 MeV iodine ions. The distribution of iodine was evaluated by using TRIM computer calculation and measured by Rutherford backscattering spectrometry (RBS) using 5 MeV 4He particle. The iodine profile was quantified after successive temperature steps. At each step the maximum temperature was held for 2 h. It was found, that the iodine profile remained unchanged up to 1373 K. At 1573 K iodine diffused significantly. The iodine profile was measurable up to 1773 K. Even at this high temperature a significant iodine retention is observed. The diffusion coefficient of iodine (3.5 ± 1.4 × 10−15 cm2 s−1) is of the same order as the temperature extrapolated data of iodine in monoclinic/tetragonal zirconia.