A series of thiol-derivatized porphyrins and the corresponding cobalt and zinc complexes were synthesized from 5-(p-aminophenyl)-10,15,20-triphenylporphyrin (H(2)TPP-NH(2)), and 5 alpha,15 alpha-bis(o-aminophenyl)porphyrin (H(2)DPE-(NH(2))(2)). These derivatized porphyrins have a different number of thiol appendages attached via amide linkages at different locations. The thiol-derivatized porphyrins made from H(2)TPP-NH(2), H(2)TPP-NHC(O)(CH(2))(n)SH (n = 2, 4, 5, 10), have one alkyl-thiol appendage attached to the porphyrin through an amide linkage on the p-aminophenyl position. The derivatives made from H(2)DPE-(NH(2))(2) have two alkyl-thiol appendages attached to the porphyrin through amide linkages on the o-aminophenyl positions on the same face of the porphyrin ring. These thiol-derivatized porphyrins are important adsorbates for the preparation of thiol-porphyrin monolayers on gold. (C) 1997 by John Wiley & Sons, Ltd.