Abstract: The release rate and release dynamics of thallium, which is used as the substitute for its ekaelement 113, are measured on the metal surfaces of Ni,Pd,Mo,Ta,Zr,Ti ,Au, Ag, Cu and Fe and non-metal surfaces of graphite and SiO2 The theoretical adsorption enthalpies of Tl on the metal surfaces mentioned above are calculated. The experimental and theoretical results are compared and the differences between them are discussed. The release behaviour and the adsorption enthalpies of element 113 on these surfaces are estimated qualitatively.