Thiosemicarbazone ligand, 2-((4,9-dimethoxy-5-oxo-5H-furo[3,2-g]chromen-6-yl) methylene) hydrazinecarbothioamide and its Cd(II), Cu(II), Zn(II), Ni(II), Co(II), VO(II), and Mn(II) complexes have been prepared and characterized by various spectroscopic and analytical techniques. Complexes molar conductance measurements displayed that all complexes (2-8) are non-electrolyte. With general compo-Based on analytical and spectral measurements, the octahedral or distorted octahedral geometries suggested for complexes. Ligand and complexes anti-proliferative activities were assessed against three various human tumor cell lines including breast cancer (MCF-7), liver cancer (HepG2) and lung cancer (A549) using SRB fluorometric assay and cis-platin as positive control. The anti-proliferative activity result indicated that the ligand and its complexes have considerable anti-proliferative activity analogous to that of ordinarily utilized anti-cancer drug (cis-platin). They do their anti-cancer activities by modifying free radical's generation via raising the superoxide dismutase activity and depletion of intracellular reduced glutathione level, catalase, glutathione peroxidase activities, escorted by highly generation of hydrogen peroxide, nitric oxide and other free radicals leading to tumor cells death, as monitoring by decreasing the protein and nucleic acids synthesis.