The solvent extraction of rhenium using TiOA as extractant assisted by ionic liquids from aqueous solutions was investigated. The molalities of ReO4- after extraction were measured at impurity ionic strength from 0.2 to 2.0 mol.kg(-1) at temperatures from 293.15 to 318.15 K in the aqueous phase. Standard extraction constants K at different temperatures were obtained by the Pitzer polynomial approximation method. Thermodynamic properties for the extraction procedure were also calculated.