A process for making defibered pulp material comprising the steps of treating fibrous ligno-cellulosic material with aqueous nitric acid or nitrate salts having a nitrate ion concentration of about 0.001 to 9.0 wt.% and containing at least one aluminum compound in an amount of at least 0.01 parts by weight of aluminum ions per each 10 parts by weight of HNO<u3>u, so as to nitrate ligneous component of said material; and thereafter defibering directly, or treating the nitrated ligno-cellulosic material with alkali to separate the ligneous component from the cellulosic pulp, and, optionally, recombining a part or all of the ligneous component with the cellulosic pulp.
