Thermogravimetric analysis, was employed to study the thermal behaviour of typha, a naturally growing plant in the marshes of the south of Iraq, and its main components, holocellulose, hemicellulose and cellulose. The overall TG signal of typha appeared as the sum of those of hemicellulose and cellulose. The conditions of holocellulose fractionation, and particularly the nitrogen purging, affected the nature of the cellulose and hemicellulose, as could be concluded from the shapes of the TG curves of these fractions. The thermal behaviour of typha is greatly influenced by the stage of maturity of the plant.