Understanding speciation is fundamental to predicting radionuclide behaviour and fate in the environment, and factors affecting speciation (pH, Eh and ligand availability) ultimately control radionuclide solubility and mobility. Speciation data are therefore required to predict the mobility of radionuclides from long-term nuclear waste-storage facilities and transport through the environment. Analytical methods such as hyphenated techniques and direct spectroscopic and mass spectrometric techniques provide such data. This article reviews recent literature, discusses analytical trends and compares and contrasts different techniques for radionuclide speciation analysis, with emphasis on long-lived species that have the highest risk of being a major long-term hazard. (C) 2007 Elsevier Ltd. All rights reserved.