Thermodynamic parameters of complex formation of alkylamides and dimethyl sulfoxide with tetraphenylporphyrinatozinc in benzene and carbon tetrachloride were determined by calorimetric titration. The composition of the complexes was also determined. Correlations were found between thermodynamic stability parameters of the complexes and physical parameters of the ligands. The effect of the ligand and solvent nature on the thermodynamics of complex formation was analyzed.