Five kinds of solid coordination complexes of uranium(VI) and thorium(IV) with the diamide (N,N,N,N
-tetrabutylmalon-amide (TBMA), N,N,N
,N
-tetrabutylsuccinylamide (TBSA), N,N,N
,N
-tetrabutylglutaramide (TBGA), N,N,N
,N
-tetrabutyl-adipicamide (TBAA)) were synthesized. All these complexes of UO2(NO3)2·TBMA, UO2(NO3)2· TBSA, [UO2(NO3)2·(TBGA1/2)2]x, UO2(NO3)2·TBAA and Th(NO3)4·2TBMA were characterized by elemental analysis, UV spectra, IR spectra and 13C NMR spectra. The coordination form and proposed structures of the complexes are also discussed.