For more than thirty years, the IAEA has published a set of documents aimed at the limitation of the radiation exposure of the population from various nuclear activities. In particular, in 1994 the IAEA published Technical Reports Series No. 364, Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments. Over the years, it has proved to be a valuable reference for radioecologists, modellers and authorities in Member States, and has been quoted in numerous impact assessments. Technical Reports Series No. 364 was based on a review of available data up to the end of 1992. However, a number of high quality critical reviews have been produced in recent years for some of the transfer parameter values which merit consideration. Thus, it was assumed that there is sufficient new information available to warrant reconsideration of a significant proportion of the values given in Technical Reports Series No. 364 and to initiate an updating of Technical Reports Series No. 364 in the framework of the IAEA EMRAS (Environmental Modelling for RAdiation Safety) project. It is expected that the revision of Technical Reports Series No. 364 will initiate further updating of related IAEA publications, and international and national radiological models. The present IAEA-TECDOC is intended to be a support to the update of Technical Reports Series No. 364, overcoming the limitations of the former, and comprises both revised transfer parameter values, as well as missing data, key transfer processes, concepts and models that were found to be important for radiation safety. The publication was prepared by members of the EMRAS project Working Group 1, Theme 1 Revision of IAEA Technical Reports Series No. 364. The group was chaired initially by P. Santucci, followed by P. Calmon. The IAEA wishes to express its gratitude to M. Thorne, A. Gondin da Fonseca and B.Varga for their kind assistance in editing and preparation of the document for publishing, and.to all the contributors to the IAEA-TECDOC and those who assisted in its drafting and review. The IAEA officer responsible for this publication was S. Fesenko of the Department of Nuclear Sciences and Applications.