Imidazolium-based ionic liquids containing cisdicyclohexano-18-crown-6 (DCH18C6) were tested for the extraction of Sr 2+ and Cs +. For Sr 2+ extraction, the influence of the addition of a sacrificial cation exchanger was also investigated. A decrease in strontium distribution coefficients in ionic liquids was observed for the system using Na + as a sacrificial ion. This observation is rationalized by the competition of Na + for crown ethers. A slight increase in strontium distribution coefficients was observed for an ionic liquid system utilizing oleic acid as the cation exchanger. This moderate increase of the strontium distribution coefficient can be attributed to the proton-mediated ion exchanging process and the potential synergistic effect of the organic acid. A series of imidazolium-based ionic liquids containing 2-alkoxy-2-oxoethyl substituents on one or both of the imidazole nitrogens was synthesized and characterized by NMR spectra. The solvent extraction results using calix[4]arene-bis(tertoctylbenzo- crown-6) [BOBCalixC6] in these ionic liquids are reported.