In order to investigate the adsorption of astatine and radon on a palladium surface some on- and off-line thermochromatographic experiments were carried out with2l0At- and220Rn-traccrs. The partial molar adsorption enthalpy for zero covering was experimentally found to beand. The results are compared with the theoretical and experimental values for other elements of the sixth period. The adsorption behaviour of At is in conformity with that of the p-metals on a palladium surface.