The thermal treatment of Fe2O3·1.65H2O gives rise to sharp dehydration weight-change waves (310–470 K and 470–670 K) which correspond to the loss of loosely-bound and stronglybound water, respectively. Analysis of the thermal waves was performed by the method of Šatava and Škvara (1969), the modified method of Coats and Redfern (1964) and the method of Blazejowski et al. (1983), and by applying a least squares straight line fit to the data. The A2 andA3 decomposition mechanisms predominate in the first dehydration step, whereas anF1 mechanism seems the best to describe dehydration of the structural water. Activation energies of 21 kJ · mol−1 and 95 kJ·mol−1 are estimated for the first and second steps, respectively.