This study investigates the transport of arsenic species through a supported liquid membrane (SLM) using Aliquat 336. Preliminary liquid-liquid extraction experiments were performed and several conditions affecting the extraction, such as the organic solvent and pH of the aqueous phase, were evaluated. The best results were obtained when using a mixture of dodecane modified with 4% dodecanol at pH 13. The experimental distribution data were numerically analysed by Letagrop-DISTR software to obtain a thermodynamic model corresponding to the extraction for both As(V) and As(III) species. Taking into account the good results obtained in liquid-liquid experiments, a supported liquid membrane (SLM) system was developed based on the best separation conditions. As(V) was stripped using 0.1 M HCl. The SLM enabled the separation of As(V) and As(III) species based on their different kinetic behaviour. The system also permitted the transport of As(V) at ppb levels and the removal of As(V) from real matrices, such as spiked tap water and river water. (C) 2010 Elsevier B.V. All rights reserved.