Functionalized ionic liquid based on quaternary ammonium salt was investigated for the specific task of the efficient extraction of f block elements in different oxidation states. It deals with the investigation of extraction efficiency, mechanism, speciation and associated kinetics and thermodynamics. The extracted species of Pu4+, PuO22+, Am3+, Eu3+ were found to be Pu(Hptha)(H2O)(6)(3+), PuO2(Hptha)(H2O)(2)(+), Am(Hptha)(H2O)(7)(2+), Eu(Hptha)(H2O)(7)(2+), respectively where (Hptha)(-) is the anionic part of the ionic liquid. Effect of radiation exposure on the performance of the ionic liquid was also investigated. The suitable back extraction procedure from the ionic liquid phase was developed using aqueous soluble complexing agents.