The kinetic and the thermodynamic characteristics of the physical and the physicochemical processes, taking place under thermal treatment of fly ash (FA) from lignite coals, were investigated. The obtained results are important for the thermal stability of this material, as well as for the determination of appropriate regimes for its zeolitization, vitrification and thermal activation. The thermal treatment is essential for the development of advanced technologies for utilization of ash residues. FA was subjected to differential thermal analysis (DTA) as the heating was performed at different rates: 2.5, 5.5, 11.0, 15.0, 25.0 and 35.0 degrees C min(-1). The obtained experimental thermograms were divided conditionally in three thermal zones: up to 200 degrees C, 200-675 degrees C and 675-950 degrees C, where the following thermal effects were registered: first zone - an endothermic effect, attributed to the water desorption and the liberation of adsorbed gases; second zone - two exothermic effects, related to the chemical oxidation of the magnetite in the FA composition; third zone - a small endothermic effect in the interval 760-861 degrees C related to the glass transition of the amorphous constituents of the FA. The activation energy E-a of the surface and the bulk oxidation of magnetite to hematite, corresponding to the exothermic peaks in the second zone, was calculated by the derived kinetic equations. The process thermodynamic parameters, such as enthalpy Delta H and entropy Delta S, were computed comparing the areas of the characteristic thermal effects of the investigated FA and an appropriate etalon. The values of E-a, Delta H and Delta S of the low- and the high-temperature oxidation were found to be (E) over bar (L)(a) = 29.3 kJ mol(-1), Delta H-L = 1.01 kJ mol(-1), Delta S-L = 1.67 J mol(-1) K-1, and (E) over bar (H)(a) = 51.7 kJ mol(-1), Delta H-H = 3.97 kJ mol(-1) and, Delta S-H = 5.05 J mol(-1) K-1, correspondingly. (C) 2013 Elsevier Ltd. All rights reserved.