The synthesis and characterization of lanthanide(III) complexes with the Schiff-base hydrazone, o-hydroxyacetophenone-7-chloro-4-quinoline, (HL) are reported. The complexes were characterized by different physicochemical methods: mass spectrometry, H-1 NMR, C-13 NMR, and IR, UV-visible, molar conductance and magnetic studies. They have the stoichiometry [Ln(L)(2)(NO3)] center dot nH(2)O where Ln = La(III), Pr(III), Nd(II), Sm(III), Eu(III) and n = 1-3. The spectra of the complexes were interpreted by comparison with the spectrum of the free ligand. The Schiff-base ligand and its metal complexes were tested against one stain Gram +ve bacteria (Staphylococcus aureus), Gram -ve bacteria (Escherichia coli), and Fungi (Candida albicans). The tested compounds exhibited high antimicrobial activities.