Optimal conditions for strontium(II) sorption by new complexing polymeric sorbents (CPSs) from aqueous solutions were studied, namely, optimal solution acidity (pH opt ), pH of 50% sorption (pH 50 ), and optimal time and temperature of quantitative sorption. The strontium(II) sorption capacities of the test sorbents (SCSs) were determined, and sorption isotherms were plotted. The strontium(II) sorption parameters determined were used to recognize the most efficient CPSs.