Seven complexes containing neutral isoorotic and 2-thioisoorotic acids, as well as thiocyanate and chloride anions as lignands, have been synthesized and characterized by means of both spectral (IR, 1H, and 13C NMR) and thermal (TG and DSC) methods, as well as conductivity measurements. Spectral data suggest that any binding metal-ligand mode for uracil derivatives is not easy to propose. Therefore, isoorotic ligands must link through some oxygen atom. Likewise, 2-thioisoorotic acid seems to be [N,S] bonded in Pd(II) and Pt(IV) complexes, whereas for Hg(II) complex a distorted tetrahedral HgCl2S2 structure has been proposed. In the cadmium complex, the metal ion exhibits a CdCl2O2 coordination sphere. Antimicrobial activities of the complexes against Pseudomonas sp, E. coli, Proteus sp, Salmonella sp, Micrococcus sp, Staphylococcus sp, Bacillus sp and Candida sp were performed as a previous step in the study of their biological activity.