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The simplest and most common parameter for modelling radionuclide mobility in soils is the distribution coefficient, Kd. In reverse, the empirical Kd value accounts for several bio-chemical and physical mechanisms, influenced by numerous correlated variables. Moreover, Kd values vary with radionuclide and soil types. Consequently, the use of default Kd values in assessment models to predict the behaviour of radionuclide in soils can result in significant uncertainties. Five radionuclides (Cs, I, Sr, Se, Tc) were systematically assessed regarding their behaviour in the soil, e.g., main processes, kinetics, sorption reversibility/irreversibility... A data base of Kd values was completed for each radionuclide, including the data used for establishing the most common default values and new data from recent publications. A summary form summarizes the most important parameters, proposes a default Kd value for and suggests pertinent experiments that could be carried out in order to acquire more relevant Kd values. © 2005 EDP Sciences.