BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste-water. In the present work, the removal of Co(II) from a synthetic CoSO 4 solution containing initial amounts of cobalt(II) in the range 100-200 ppm (0.1-0.2 g dm −3 ) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined.