AbstractThe tautomerism of several aminomethyl‐phenols and‐naphthols in aqueous solution is studied, using electron absorption spectroscopy. From the UV‐VIS‐spectra at different pH‐values both pK‐values can be calculated, together with the proton transfer equilibrium constant KPT, At neutral pH the aminomethyl‐phenols and‐naphthols exist mainly as zwitter ions without intramolecular hydrogen bond. Log KPTfollows a linear r