Five organotin(iv) compounds Ph3SnL (1), (R2Sn)4O2L4 [R = n-Bu (2), n-Oct (3)], (R2Sn)4O2L2Cl2 [R = n-Bu (4), Me (5)], HL = 2-phenyl-4-selenazole carboxylic acid, were synthesized, of which triphenyl- and di-n-butyltin(iv) compounds display higher in vitro cytotoxicities.