The synergism in the extraction of Sr⊃ +⊃ from 0.5M Sr(NO⊂3⊂) ⊂2⊂ by 0.05M dicyclohexano-18-crown-6 (DC18C6) + 0.1M Versatic 1519 (abbreviated v-acid or RCOOH, a neo carboxylic acid) in CCl⊂4⊂ has been found to stem from a strong 1:1 interaction between DC18C6 and Sr⊃2+ ⊃ However, both nitrate and carboxylate can function as the anion for the (DC18C6)Sr⊃2+⊃ moiety. At aqueous conditions corresponding to less than complete loading (i.e., [Sr⊃2+⊃[ org < 0.05M for pH < 11.7), (DC18C6)Sr(NO⊂3;)⊂2⊂ precipitates as a solid. As the pH is raised in the interval 7 < pH < 11.7 to deprotonate the V-acid, the precipitate (DC18C6)Sr(NO⊂3⊂) ⊂2⊂ becomes solubilized first with probable formation of a mixed-anion complex and finally with quantitative (0.05M) formation of the monoraeric complex (DC18C6)Sr(OOCR) ⊂2⊂ H⊂2⊂O at pH = 11.7 as confirmed by viscometric titration of 0.05M DC18C6 in wet CCl⊂4⊂ with Sr(OOCR) ⊂2⊂, Karl-Fischer titrations, vapor-phase osmometry, and IR spectrophotometry.