The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyses, electrical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass spectra. Nephelauxetic ratio, covalency parameter and bonding parameter for these complexes were also calculated. The probable structures of the complexes were proposed. The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds. The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln (L) 3] (Ln = La (Ⅲ) or Pr (Ⅲ); LK = potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyzes, electrical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds.