Twelve lipophilic, acyclic polyethers, each with two terminal N-(X)sulfonyl carboxamate groups, are found to efficiently extract Ra(II) and Ba(II) at radiotracer levels from aqueous solution into chloroform. With the presence of Ba(II) carrier in the aqueous feed solution, very appreciable Ra(II)/Ba(II) selectivity is observed in single-stage, liquid-liquid extraction for the polyether that combines the largest polyether pseudo-cavity and the most acidic ionizable group.