Environmentally benign aqueous biphasic systems (ABS) are recognized as green systems in analytical research. In this study, a salt–salt ABS composing of water soluble ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([bmim]Cl) and kosmotropic salt K2HPO4 have been used for the separation of no-carrier-added (NCA) 203Pb from proton irradiated natTl2CO3 target. The optimum separation condition was obtained with 1 min shaking and 10 min settling time of the ABS, where ~60 % of NCA 203Pb was extracted into the IL rich phase with nominal contamination from bulk Tl. The reported separation technique is simple, rapid and meets the demands of green chemistry.