Competitive solvent extraction of the mixure of alkali metal and alkaline earth cation from water into organic solvent containing the crown ether carboxylic acid and anlogous crown ether phosphonic acid was investigated as follows. The lipophilic group is found to strongly influence to the selective extraction in the mixed systems from only alkali metal cation for sym-(n-decyldibenzo)-16-crown-5-oxyacetic acid $underline{1}$ to mostly alkaline earth metal cation for sym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxyacetic acid $underline{3}$. Monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $underline{2}$. and monoethyl-sym- bis]4(5)-tert-butylbenzo]-16-crown-5-oxymethylphosphonic acid $underline{4}$ showed good selectivity for $Na^+$ over $Mg^{2+}$, the second extracted ion. Structural variation in the crown ether phosphonic acid somewhat was influenced to the extraction selectivity in the mixed systems. when variation of the ionized group is influenced in the mixed systems, the selectivity of $Na^+$ as the second extracted ion was much better crown ether carboxylic acid $underline{1}$ than crown ether phosphonic acid $underline{2}$, while the efficiency of $Na^+$ extraction was better $underline{2}$ (83% total loading) than $underline{1}$ (32%).