Abstract: Process for enriching the organic nitrogen content of commercial scale quantities of cellulosic materials which includes the steps of: a) placing substantially dry or unwetted cellulosic material in a pressurizable reactor; b) injecting an ammonia or ammonia-forming nitrogen solution into the reactor until the cellulosic material is approximately submerged; c) setting the temperature in the reactor to maintain a liquid temperature between about 80 and 200° C.; d) pressurizing the reactor to at least 750 psi; e) maintaining the temperature and pressure in the reactor for a period of time sufficient for the organically bound nitrogen content of the cellulosic material to exceed about 1.5%; and f) drying the cellulosic material to a moisture content sufficiently low to arrest microbial activity.