When nitrocellulose is used in the production of gun powders and rocket/missile propellants, rigid control of the cellulose nitration reaction is necessary. Nitrogen content is, by far, the most important parameter to be controlled and only off-line measurements can be performed for that. Although cellulose is a natural polymer whose characteristics may vary, the final product must have its nonuniformities compensated by blending of different batches. In this work, kinetic and mass-transfer parameters are nonlinearly fitted using typical nitration experiments. The required mathematical modeling is carried out using a continuous mixtures approach, which depends only on structural descriptions of the cellulose. The model leads to an algebraic-integro-differential population balance system of equations, solved with an approximant built with block-pulse functions. (c) 2006 American Institute of Chemical Engineers.