The organotin flufenamates [Me 2 (flu)SnOSn(flu)Me 2 ] 2 (1), [Bu 2 (flu)SnOSn(flu)Bu 2 ] 2 (2) and [Bu 2 Sn(flu) 2 ] (3) have been prepared and structurally characterized by means of vibrational and NMR ( 1 H, 13 C and 119 Sn) spectroscopy. The crystal structure of [Me 2 (flu)SnOSn(flu)Me 2 ] 2 (1) has been determined by X-ray crystallography. Three distannoxane rings are present to the dimeric tetraorganodistannoxane of planar ladder arrangement. The structure is centro-symmetric and features a central rhombus Sn 2 O 2 unit with two additional tin atoms linked at the O atoms. Six-coordinated tin centers are present in the dimer distannoxane. This structure is self-assembled via π→π and C–H→π stacking interactions. Flufenamic acid and flufenamates were evaluated for antiproliferative activity in vitro. Among the compounds tested [Bu 2 (flu)SnOSn(flu)Bu 2 ] 2 (2) and [Bu 2 Sn(flu) 2 ] (3) exhibited high cytotoxic activity against the cancer cell line A549 (non-small cell lung carcinoma).