A team at HZB has developed a method of experimentally unraveling tautomeric mixtures. Based on resonant inelastic X-ray scattering (RIXS) at BESSY II, not only proportions of the tautomers can be deduced, but the properties of each individual tautomer can be studied selectively. This method could yield to detailed information on the properties of molecules and their biological function. In the present study, now advertised on the cover of The Journal of Physical Chemistry Letters, the technique was applied to the prototypical keto-enol equilibrium.