5,10,15,20-Tetrakis[4-(triorganostannyloxy)phenyl]porphyrins, (R3SnO)4TPP [2, R = Cy (a), Ph (b), PhC(CH3)2CH2 (c)], have been synthesized by the condensation of 4-(triorganostannyloxy)benzaldehyde, 4-(R3SnO)C6H4CHO (1), with pyrrole in the presence of BF3 followed by oxidation by p-chloranil and characterized by means of elemental analysis, IR, UV–visible and NMR (1H, 13C and 119Sn) spectra. The results of X-ray single-crystal diffraction show that 1a and 1b possess a trans-C3SnO2 trigonal bipyramidal geometry with the axial positions occupied by the phenolate oxygen and formyl group oxygen of an adjacent molecule and form a one-dimensional zigzag chain. In 2a, the macrocyclic core of the porphyrin is coplanar and each tin atom possesses a distorted tetrahedral geometry. These compounds (1 and 2) have potent in vitro cytotoxic activity against two human tumor cell lines – CoLo205 and MCF-7 – and the activity decreases in the order Ph > Cy > PhC(CH3)2CH2 for the R group bound to tin. Copyright © 2013 John Wiley & Sons, Ltd.