Experiments were conducted on equilibrium distribution of citric acid between relatively concentrated aqueous solutions and macroporous resins containing tri-n-octylamine (TOA). The equilibrium data were well described by the Langmuir isotherm equation. Chemical model analysis of the results showed that the sorption could be also explained by the formation of an acid-amine complex with general composition (acid)(TOA)q in the resin phase. The loss of amine from the impregnated resins and the effect of temperature on equilibrium distribution were also discussed.