Abstract: The extraction process based on chemical complexation is of higher capacities and selectivities for dilute polar organic solution.In this work,phase equilibrium governing the reactive extraction of maleic acid from aqueous solution into solutions of TOA in the diluents chloroform,4-methyl-2-pentanone (MIBK), n -hexane and n -octanol was investigated.The results showed that the influence of the diluents on extraction depended on the concentration of maleic acid.Protonation diluent was more effective than others in low equilibrium concentration of maleic acid.In high equilibrium concentration of maleic acid,the sequence of extraction capacity was MIBK> n -octanol> n -hexane>chloroform.Overloading existed and the sequence was MIBK> n -octanol> n -hexane>chloroform.FT-IR spectroscopic analysis of organic samples loaded with maleic acid was carried out,the results showed that amine formed 1∶1 complexation with maleic acid.