Abstract: Ion chromatography was applied to the determination of sodium sulfate (as SO2-4 ion) in additives for concrete.The additive sample was dissolved in water.The RP column was used to remove organic substances from the sample solution.An aliquot (25 μL) of the eluate from RP column was taken for IC determination.The Dionex IonPac AS18 column was used for separation,and 30 mmol·L-1 KOH solution was used as mobile phase with flow-rate of 1.0 mL·min-1.Not only SO2-4 ion,but also Cl- ion was determined simultaneously by this method through measuring values of peak area.Detection limit (3S/N) found was 3 μg·L-1.Precision of the method was tested at 3 concentration levels,value of RSD′s (n=6) found were less than 1%.Values of recovery found by standard addition method were in the range from 98.7%-100.5%.