This work applied lanthanide ions to simulate the actinides in order to use the room temperature ionic liquids as the electrolytes as a substitute for chloride high temperature molten salt to attain the goal of reducing the actinide such as uranium or plutonium?in the nonaqueous reprocessing applications of spent nuclear fuel. The electrochemical behavior of La(III) in the ionic liquid, N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2), has been investigated by cyclic voltammetry. The results indicate that the reduction of La(III) is irreversible. The diffusion coefficient and the energy of activation of La(III) in ionic liquid MPPiNTf2 are 2.79×10-7 cm2/s at 323 K and 99.4 kJ/mol, respectively. Controlled potential electrolysis of a solution of La(Ⅲ) in MPPiNTf2 at –2.9 V (vs.Pd) results in the deposition of metallic lanthanum.