In a study of three non-wood pulps (rice straw, EFB, and Hesperaloe), the standard pyrolysis model for biomass based on hemicellulose, cellulose, and lignin pseudo-components, was modified to include char volatilization. As a result, abnormally high values for lignin content have been avoided. On the other hand, the consideration of autocatalysis (Prout-Tompkins equation) for TGA data simulation under inert and oxidative atmospheres, allows obtaining a stable set of kinetic parameters that describe volatilization and char oxidation for different heating rates, including char ignition. These simulations allow us to investigate certain effects like oxygen influence on cellulose-char formation (including reduction in activation energy) and to calculate the composition of samples. (C) 2009 Elsevier Ltd. All rights reserved.