ester and N-[4-(2-amino-3-hydroxy-pyridin-6-ylazo)phenyl]-acetamide compounds were studied. The dissociation constants were determined potentiometrically. The thermodynamic parameters of dissociation were evaluated. Regression analysis is applied for correlating the different parameters. The results help to assign the solute-solvent interactions and the solvatochromic potential of the investigated compounds. The electronic character of the substituent and the chemical nature of the solvent are major factors for the observed solvatochromism. Nitroso Pyridin-6-ylazo Triazene Effect of solvents Potentiometry Spectrophotometry