The pulsed-neutron-source and time-of-flight spectrometers at ISIS have raised incoherent inelastic neutron scattering to the state of a major technique in vibrational spectroscopy. INS has brought new information on the proton dynamics in solids. New entities like free protons, tetrahedral (H +) 4 and H 3O +, etc. have been characterised. Quantum proton transfer along hydrogen bonds has been revealed. The full S( Q, ω) maps of intensity shed new light on the vibrational wave functions.