Abstract: The release behaviors of 204T1 from the metal surfaces of Cu, Ag, Au, Zr, Ti, Ta, Mo, Pd, Ni and stainless steel and non-metal surfaces of SiO2 and graphite are studied. The adsorption enthalpy of 204T1 on these metal surfaces are calculated with a theoretical formula. The comparison of experimental results with the theoretical adsorption enthalpy of T1 on the metal surfaces shows that the release rate of T1 decreases with increasing adsorption enthalpy.