This study consists of the synthesis of cadmium (II) and mercury (II) metal complexes of ONNO-type Schiff bases. Two different ONNO-type Schiff bases were prepared. One cadmium(II) and one mercury(II) complex of the considered Schiff bases were achieved. Both are proved to be mononuclear complexes. Ligands and complexes were analyzed via melting point determination, elemental analyses, thermogravimetric (TG) analysis, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. Moreover, structural and energetic analyses for both complexes have been realized using Hartree-Fock (HF) and density functional theory (DFT) methods with CEP-121G basis set.