Thermogravimetric analysis was used to examine the dehydroxylation of medium-ordered kaolin in non-isothermal conditions. A series of thermogravimetric experiments was conducted at temperatures ranging from 25 °C to 800 °C. The kinetic model describing the reaction mechanism and the key kinetic parameters, including the pre-exponential factor (A) and apparent activation energy (E_a), were determined. Depending on the heating rate, linearization of the collected data shows that the dehydroxylation of kaolin and the production of metakaolin can occur at temperatures of 400 °C–500 °C. The total activation energy of the dehydroxylation process was found to be 154.16 kJ·mol⁻¹ for Kissinger–Akahira–Sunrose, 165.16 kJ·mol⁻¹ for Flynn–Wall–Ozawa, and 154.81 kJ·mol⁻¹ for Starink, with frequency factors ranging from 1.75 × 10¹¹ to 1.54 × 10¹² min⁻¹. The thermodynamic study revealed that kaolin thermal degradation is an endothermic and non-spontaneous process, driven by third-order chemical reactions and three-dimensional diffusion mechanisms (ΔH = 147.976 – 158.977 kJ·mol⁻¹, ΔG =190.930 – 198.741 kJ·mol⁻¹, and ΔS = −62.722 − 53.497 J·mol⁻¹ K⁻¹). These findings provide a kinetic and thermodynamic basis for predicting kaolin dehydroxylation behavior and optimizing calcination conditions for efficient metakaolin production.