The separation behavior of rhenium from hydrochloric acid medium by a solution of TiOA in ionic liquid, [Csmim][NTf2], was researched. At temperatures from 293.15 to 318.15 K, the equilibrium molalities of ReO4- were measured at ionic strength from 0.2 to 2.0 mol-kg(-1) in the aqueous phase. The standard extraction constants K-0 at disparate temperatures were gained by the Pitzer polynomial approximation method. Thermodynamic quantities for the extraction procedure were also calculated.