Dehydration of halloysite (Hly) to metahalloysite (m-Hly) was examined by X-ray diffraction (XRD). The Hly samples heated in temperature range of 80–400 ℃. The heating time (t) at each temperature was changed up to 420 min. The peak intensities (I) for the basal spacing (d₀₀₁) of Hly (1.0 nm) and m-Hly (0.7 nm) were determined. The variation of the intensities with the heating time was evaluated for each temperature. The full heating time (t_f) for each completed crystal transformation was determined graphically and used as kinetic variable. The rate constant (k) was evaluated as \(k=1/{t}_\text{f}\) for the crystal transformation assumed from the zeroth order (n = 0). It has been observed that the drawn lnk-1/T graph conforms to the Arrhenius equation in the form of \(\mathrm{ln}k=-3247.2/T+3.4215\). The activation energy was calculated as E^# = 27 kJ mol⁻¹ from the slope of this line equation, and the frequency factor from its intercept was calculated as A = 31 min⁻¹.