There is considerable interest in thiosemicarbazone ligands due to their strong affinity for a diverse range of metal ions1 and their coordination versatility deriving from their propensity to undergo base-/metal-assisted tautomerization. Moreover, their inherent multifarious pharmacological behavior is enhanced upon complexation with bioactive transition-metal ions. In this research endeavor, ternary thiosemicarbazone complexes of oxovanadium(IV) and copper(II) with the bidentate heterocyclic co-ligands 1,10-phenanthroline (phen) and 2,2´-bipyridine (bipy) (or their derivatives) were designed, synthesized and characterized by a wide range of physicochemical techniques. Crystallographically elucidated ternary thiosemicarbazate oxovanadium(IV) complexes2–4 are very rare indeed; herein we present single-crystal X-ray structures of the corresponding oxovanadium(IV) thiosemicarbazone complexes hitherto nonexistent. These oxovanadium(IV) complexes and their copper(II)5 counterparts have been investigated for antiproliferative activity in HeLa and MCF-7 cancer cell lines in the presence and absence of visible electromagnetic radiation. Moreover, in some cases, selectivity involving the MCF-10 normal cancer cells has been investigated with fascinating findings.