Thallium(I) complexes of 2,3,7,8,12,13,17,18-octaethylporphyrin and 5,10,15,20-tetraphenylporphy-rin are shown to have two thallium(I) ions per porphyrin ligand. Syntheses, spectroscopic characteristics (UV-vis, MS, NMR), chemistry, and an X-ray crystal structure of bis-thallium(I) porphyrins are presented.