The 2-methylimidazole complexes of Co(II), Ni(II), Cu(II) and Zn(II) orotates, mer-[Co(HOr)(H2O)(2)(2-meim)(2)] (1), mer-[Ni(HOr)(H2O)(2)(2-meim)(2)] (2), [Cu(HOr)(H2O)(2)(2-meim)] (3) and [Zn(HOr)(H2O)(2)(2-meim)] (4), were synthesized and characterized by elemental analysis, spectral (UV-Vis and Fr-IR) methods, thermal analysis (TG, DTG and DTA), magnetic susceptibility, antimicrobial activity studies and single crystal X-ray diffraction technique. The complexes 1 and 2 have distorted octahedral geometries with two monodentate 2-methylimidazole and one bidentate orotate and two aqua ligands. The complexes 3 and 4 have distorted square pyramidal and trigonal bipyramidal geometry, respectively, with one 2-methylimidazole, bidentate orotate and aqua ligands. The orotate coordinated to the metal(II) ions through deprotonated nitrogen atom of pyrimidine ring and oxygen atom of carboxylate group as a bidentate ligand. The antimicrobial activities of 1 and 4 were found to be more active gram (+) than gram (-) and 4 could be use for treatment Staphylococcus aureus. (C) 2009 Elsevier Ltd. All rights reserved.