Four new organotin(IV) complexes [(Bu 3 Sn)(FcCOO)] n (1), [(μ-Bu 2 Sn) 2 (μ-Bu 2 SnFcCOO) 2 (μ 3 -O) 2 (μ-OCH 3 ) 2 ] 2 (2), [Ph 3 Sn(FcCOO)(H 2 O)](phen) (3) and [{Ph 3 Sn(FcCOO)} 2 (4,4′-bipy)] (4) [Fc=(η 5 -C 5 H 5 )Fe(η 5 -C 5 H 4 )] have been synthesized and characterized by elemental analyses, IR, ( 1 H and 13 C) NMR spectra and X-ray single-crystal diffraction analyses. The structure analyses show that all tin atoms in complexes 1–4 are five-coordinated with trigonal bipyramid geometry. Complexes 1–4 and FcCOOH undergo reversible one-electron oxidations in methanol solution. The antitumor activities of complexes 1–4 have also been tested. Complexes 1 and 2 exhibit medium activity towards P388 cell lines and Hela cell lines. Complexes 3 and 4 exhibit medium activity towards P388 cell lines but strong activity towards Hela cell lines. This may result from complexes 3 and 4 including the neutral molecules 1,10-phenanthroline and 4,4′-bipy.