This paper reports a first-ever cyclic voltammetric study and the electrochemical characterization of Np(IV) complexes with task-specific ionic liquid with appended diglycolamide (DGA-TSIL) ligand dissolved in the room-temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C4mimNTf2). The results are compared with molecular entity, N,N,N′,N′-tetraoctyl diglycolamide (TODGA) dissolved in the same diluent. The diffusion coefficient (D) values were determined using the Randles–Ševcik equation. The standard rate constant (k s) values were also computed for the Np(IV)/Np(III) electrode redox reaction. The activation energy for diffusion (E a) and thermodynamic parameters for the redox reactions of the Np complexes were determined and compared.