[en] The Th(IV), Ce(III), In(III) and UO₂²⁺ complexes of Schiff bases derived from 2-amino-5-phenyl-1,3,4-thiadiazole and salicylaldehyde (L₁), p-hydroxybenzaldehyde (L₂) and vaniline (L₃), have been prepared and investigated by conductometric, spectrophotometric and microanalytical methods. It is concluded that the molecules of the ligand are coordinated to the metal ion as bidentate molecules. L₁ is coordinated through the iminic nitrogen and phenolic oxygen atoms. L₂ and L₃ are bonded through the two ring-nitrogen atoms. The complexes behave as 1:1 and 1:2 electrolytes in DMF solution