Iodine and tin are important elements in performance assessment of geological disposal of radioactive wastes. Sorption experiments of iodine were carried out under varying nitrate concentration with a range of 0 to 5 mol dm$^{-3}$ at neutral pH range in order to determine the distribution coefficient of iodine was zero or non-zero value. The experimental results with estimated statistical errors showed non-zero values for tuffaceous sandstone except for NaNO$_{3}$ concentration 0.5 mol dm$^{-3}$. Non-zero values were also obtained under NaNO$_{3}$ concentrations higher than 0.5 mol dm$^{-3}$ for granodiorite. Sorption experiments of tin were carried out at high pH range in order to check whether the distribution coefficient of tin decreases significantly with pH as a result of formation of anionic hydrolysis species of tin. The distribution coefficients of tin on granodiorite decreased from 9.79$\times$10$^{-2}$ m$^{3}$ kg$^{-1}$ at pH10.4 to 2.46$\times$10$^{-3}$ m$^{3}$ kg$^{-1}$ at pH12.4. The distribution coefficient of tin on tuffaceous sandstone was about one order of magnitude higher (about 2$\times$10$^{-2}$ m$^{3}$ kg$^{-1}$) than that of granodiorite at pH around 12.4.