Facilitated transport of Cs-137 across supported liquid membranes (SLM) containing a calix-crown ligand viz. calix[4]arene-bis(crown-6) (CC), calix[4]arene-bis(o-benzocrown-6) (CBC) or calix[4]arene-bis(napthocrown-6) (CNC) was investigated. The feed consisted of dilute nitric acid solutions while the carrier solutions contained mainly CNC in several organic diluents inside the pores of polypropylene (PP) as well as PTFE flat sheet membranes. PTFE membranes containing CNC in a diluent mixture of 2-nitrophenyloctyl ether (NPOE) and n-dodecane were found to have high stability. Selectivity studies were carried out using simulated high level waste (SHLW) as well as fission products obtained from an irradiated natural uranium target.