ABSTRACT The extraction of Np4+ was studied by a series of N-pivot tripodal diglycolamides, with varying substituents (alkyl groups with varying branching and chain length) and varying spacer length, dissolved in an ionic liquid, i.e. [C4mim][Tf2N]. Out of a series of four ligands, L I (propylene spacer) and L II (ethylene spacer) differ only in the spacer length connecting the three diglycolamide units with the tripodal N platform. While L II – L IV have the same spacer length (ethylene spacer), but L II has a hydrogen atom, L III has methyl group, and L IV has isopropyl group as a substituent at the amidic N atom close to the central N atom. A reversal extraction mechanism of Np4+ was observed when the spacer chain length reduced from a propylene group in L I to an ethylene group in L II – L IV . While a cation-exchange mechanism was observed in case of L I , a solvation extraction mechanism was seen for the other three ligands with the extracted species being Np(NO3)2(L)2+ for L I , and [Np(NO3)4·L] for L II – L IV . The extraction efficiencies of Np4+ with L II – L IV were significantly affected by the nature of the alkyl substituents and follow the order: L II > L III > L IV . This trend in the extraction pattern affirms that the alkyl substitution at the amidic N atom creates steric strain in the ligand while complexing with the metal ion.