The aim of this study deals with understanding the structural and textural evolution of the dehydrated states of the 10-Angstrom unstable hydrate of kaolinite. The method used is based on the comparison between the experimental and calculated XRD and SAXS profiles. The study is carried out in two steps: (1) the 00l reflections showed that the dehydrated states are made up of two demixed phases. The first one is related to the 10 Angstrom hydrate characterized by 2 water molecules per Si2Al2O5(OH)(4) and situated at 7.1 Angstrom from the surface oxygen's The proportion of this phase decreases during dehydration. The second phase is a randomly mixed-layer between the d-spacings 10 Angstrom, 8.4 Angstrom hydrated layers and a 7.2 Angstrom dehydrated kaolinite, the proportions of these distances change during all dehydration states. The proportion of the second phase increases during the dehydration. (2) the study of the hkl reflections with h and/or k not equal0 allowed us to characterize the structural evolution in the (a, b) plane due to the interstratification of the hydrated and dehydrated layers. The first results showed that, in addition to the translation due the mixed-laying effect, we must introduce other translation defects such as +/-b/3 in the (a, b) plane.