Thermogram profiles of a number of papermaking pulps are examined. Differences between the profiles are attributed to variations in hemicellulose content and in apparent crystallinity. Differential rate of weight loss vs. weight fraction plots indicate reaction orders between 0 and 1. Changes in the thermogram with changes in the rate of heating show evidence of competitive reactions which may be more clearly differentiated by using more extreme heating rates. The apparent crystallinity of some aged pulps increased over that of unaged controls, indicating a preferential decomposition of the amorphous regions. See also AATA 15-389.