A conformational analysis of usnic acid by Inelastic Neutron Scattering spectroscopy is envisaged, aiming at a better understanding of the equilibrium between inter- and intramolecular hydrogen-bonds, and of the keto-enol tautomerism at physiological conditions, which are responsible for the structural preferences of the compound and therefore for its activity. The INS results thus obtained will complement previous studies performed by optical vibrational methods (Raman and FTIR) and by quantum mechanical (DFT) calculations.