Electrochemical studies on [UO 2 (DMF) 5 ] 2+ , UO 2 (acac) 2 DMF, and UO 2 (salen)DMF (DMF=N ,Ndimethylformamide, acac=acethylacetonate, and salen=N ,N-disalicylidene-ethylenediaminate) complexes in DMF containing tetrabutylammonium perchlorate as supporting electrolyte have been carried out by using cyclic voltammetry to compare the stabilities of the reduction products of U(VI) complexes with unidentate or multidentate ligands. The [UO 2 (DMF) 5 ] 2+ , UO 2 (acac) 2 DMF, and UO 2 (salen)DMF complexes were found to be quasi-reversibly reduced to U(V) species. The formal redox potentials (E o , vs. ferrocene/ferrocenium) for the U(VI)/U(V) couple were determined to be −0.89 V for [UO 2 (DMF) 5 ] 2+ , −1.47 V for UO 2 (acac) 2 DMF, and −1.67 V for UO 2 (salen)DMF. The U(V) species formed in the reduction of [UO 2 (DMF) 5 ] 2+ complex is not stable and further reduced to UO 2 , while those generated in the reduction of UO 2 (acac) 2 DMF and UO 2 (salen)DMF complexes can exist stably in DMF.