The new 2,4-dithiobiuret (Hdtb) complexes Cu(Hdbt)X·DMF (X = Cl, Br, I), Cu(Hdtb) 2A (A = ClO 4, NO 3, Cl) and Cu 2(Hdtb) 3SO 4 have been prepared. The crystal structure of the Cu(Hdtb)Cl·DMF complex has been determined: copper atom has a trigonal pyramidal coordination with three short basal bonds Cu(S, S, Cl) and one axial longer CuS bond. Two ν(CuS) and one ν(CuX) band have been identified in the i.r. spectra of the Cu(Hdtb)X·DMF complexes and two ν(CuS) bands in the spectra of the Cu(Hdtb) 2A and Cu 2(Hdtb) 3SO 4 complexes. The Cu(Hdtb)X (X = Cl, Br, I) complexes have been prepared again from ethanol solutions in different conditions and show three types (A, B, C) of far-i.r. spectra. The chloride always shows the (A) type. The bromide shows both the (A) and (B) types depending on the preparation conditions (presumably the Cu/L ratio used in the preparation). A transition from the (A) to the (B) type is observed in the solid state at room temperature for the bromide complex. A tentative explanation of this fact is discussed. The CuLI complex prepared at room temperature shows only the type (B) spectrum but prepared at 80°C shows a third far-i.r. spectrum (C). It is confirmed that in all the Cu(Hdtb)X (X = Cl, Br, I) complexes the ligand is S,S-coordinated to the metal.