In this study, a new series of cadmium halide/pseudohalide complexes with a novel Schiff base ligand containing imidazolidine ring has been successfully synthesized.The structure of the ligand and its complexes was characterized by analysis tools such as Fourier transform infrared, UV-visible, proton and carbon nuclear magnetic resonance spectra, molar conductance, and thermal analysis. Also cadmium bromide and iodide nanostructure complexes have been prepared via sonochemical method. X-ray powder diffraction and scanning electron microscopy techniques confirmed nanostructure sheets for these 2 cadmium complexes. All the newly prepared compounds were screened for their antimicrobial activities, against 4 bacterial and 2 fungal strains using disk diffusion and serial dilution methods. The CdL(N 3 ) 2 and CdLCl 2 complexes showed the best antimicrobial activity as compared with other compounds. Moreover, DNA cleavage potential of all compounds was investigated by agarose gel electrophoresis method. The results showed remarkable ability of some cadmium complexes for DNA cleavage. Furthermore, thermal behaviors of all cadmium complexes were studied in the range of room temperature to 800°C under nitrogen atmosphere. The complexes were thermally decomposed via 2 to 4 steps. Cadmium metal was suggested as final residue at the end of thermal decomposition process.