The thermal decomposition of kaolinite was studied by differential thermogravimetry (DTG) technique under non-isothermal conditions. Samples of industrially treated (washed) kaolin with high content of the medium ordered kaolinite were calcined using a heating rate from 1 to 40 K min(-1). The apparent activation energy and frequency factor for the dehydroxylation of kaolinite was evaluated by Kissinger method as 195 +/- 2 kJ x mol(-1) and (8.58 +/- 0.33) x 10(14) s(-1). respectively. Avrami exponent of the process was estimated using Kissinger empirical kinetic models and Came equation. (C) 2010 Elsevier B.V. All rights reserved.