Organotin compounds especially the dialkyltin derivatives are reported to possess anti-tumour properties. The diorganotin(IV) complexes of the type Me2SnL1, Me2SnL2, Bu2SnL1, Bu2SnL2 and Ph2SnL1 (L1 and L2 is the anion of the thiosemicarbazone ligand formed by the condensation reaction of 2,3-dihydroxybenzaldehyde with thiosemicarbazide or its N(4)-methyl substituent) were synthesized using 1:1 metal-to-ligand reactant ratios. The newly synthesized complexes were characterized using elemental analysis, infrared and nuclear magnetic resonance (1H, 13C, 119Sn) spectroscopic techniques. Complex formation between the organotin(IV) moiety and the anions of 2,3-dihydroxybenzaldehyde thiosemicarbazone and 2,3-dihydroxybenzaldehyde 4-methylthiosemicarbazone occurred with chelation at the o-dihydroxy positions. The complexes are proposed to have tetrahedral geometry.