Three new triorganotin(IV) complexes of valproic acid (vp1, Me3Sn-valproate; vp2, Bu3Sn-valproate;vp3, Ph3Sn-valproate) have been synthesized and investigated by spectroscopic and biological methods.An anionic, monodentate valproate ligand was observed, ester-like coordinating the tin atom on a tetracoordinated,monomeric environment. The structures, though, can distort towards a penta-coordination, as aconsequence of a long range O · · · Sn interaction. Crystallographic and NMR findings confirm this situationboth in solid state and solution. Biological finding evidenced a clear cytotoxic action of the complexes in hepatocellularcarcinoma cell cultures: one of the complexes induced an 80% cell viability reduction after 24 htreatment in HepG2 cells. This effect was accompanied by the appearance of biochemical signs of apoptosis. InChang liver cells, the same compound induced only modest effects, suggesting a potential use as anti-cancerdrug. Preliminary evaluations on hyperacetylation state of histone H3 in tributyltin-valproate treated HepG2cells showed an increase in Ac-H3 (histone H3 acetylated at lys-9 and lys-14), suggesting that the compoundmaintains the deacetylation inhibition activity of its ligand valproate.