Nine tailored extractants containing bis-succinamide (BisSCA) skeleton have been synthesized and identified by NMR and HRMS. The extraction of U(VI), Th(IV) and Eu(III) using the present extractants was evaluated in nitric acid solution. The effect of alkyl groups attached to either the central or terminal nitrogen atoms of amide was investigated in view of the extraction efficiency. The results of slope analyses (logD vs. log[BisSCA]) suggested the formation of major complexed UO2(NO3)(2)center dot(BisSCA) species. ESI-MS spectrum further confirmed that BisSCA extractant formed 1:1 complex with uranyl ion. FT-IR spectra before and after the extraction also revealed that C=O groups and C-O-C group of ligand participated in complex reaction of uranyl cation. The comparative extraction of U(VI), Th(IV) and Eu (III) demonstrated that good separation factors were obtained in 132.6 for U/Eu and 166.6 for Th/Eu.