Novel copper(II) and nickel(II) complexes were newly synthesized by template condensation using 2-amino-3,5-dibromo- or 2-hydroxy-5-bromo-benzaldehyde S-propyl thiosemicarbazones as starting materials. The complexes with asymmetric donor atom set were identified through use of analytical and spectroscopic methods (IR, H NMR, ESI-MS and X-ray crystallography). Cytotoxicity potents of the N3O and ON3-type complexes were determined on melanoma B16F10 and fibroblast BJ ATCC CRL-2522 cell lines. The cell lines were exposed to the complexes in the concentration range of 6-500 mu M for 24 h. The results indicated selective effect of the nickel and copper complexes in favor of healthy cells. Namely, relative low concentrations of the test molecules resulted in cytotoxic effects on malignant cells while higher concentrations were required for normal cell death. The nickel complexes were more effective than the copper complexes and a nickel complex (1a) showed selectively cytotoxcity by IC50 value of 1978 mu g/ml on B16F10 cells compared to the 5464 mu g/ml value of CRL-2522 cells.