Eight European laboratories with access to five different thermogravimetric analyzers participated in this round-robin study of Avicel PH-105 cellulose pyrolysis at 5 and 40 degrees C/min: Agreement between the laboratories on the temperature (T-peak) associated with the maximum rate of weight loss at 5 degrees C/min was good. Less agreement was obtained on the residual char yield. At 40 degrees C/min, the scatter associated with measurements of Tpeak and the char yield increased. Good fits to each weight loss curve were obtained by use, of a kinetic model based on an irreversible, first-order reaction with a high (ca. 244 kJ/mol) apparent activation energy (E). Variations in values off and the preexponential constant (A) are attributed to variations in thermal lag between the various instruments and at different heating rates. Kinetic parameters are presented which offer a good fit to the 5 degrees C/min round-robin data and which prescribe an envelope that contains the data. We recommend that future studies of biomass pyrolysis by thermogravimetry include an analysis of Avicel PH 105 cellulose at 5 degrees C/min and a comparison of the resulting weight loss curve with the curves presented herein.