Calculations of energy transfer (kerma) for neutrons from thermal to 18-MeV energy have been carried out for hydrogen, carbon, nitrogen, and oxygen and for ten compounds or mixtures including tissue. All pertinent nuclear reaction processes are included. The calculation demonstrates the importance of (n, charged particle) reaction processes which have been neglected in nearly all previous calculations. These processes dominate the energy transfer process in carbon, nitrogen, and oxygen above roughly 10 MeV.