The complexation of zinc octaalkylporphyrin with mono-, di-, and triethylenediamines in toluene was studied by spectrophotometry using the molar ratio method and by 1H NMR. The effect of the structure of the two-center organic base on the formation of 1 : 1 or 2 : 1 metal porphyrin-ligand complex was established. The stability constants of the resulting complexes were calculated and the concentration ranges of their existence were determined.