In this research, thermogravimetric and mass-spectrometric (TG-MS) analysis and kinetics of different sized (60 mu m,800 mu m, and 3 mm) Saray (Turkish origin) coal is examined at various combustion temperature ranges. Experiments are performed at the heating rate of 40 degrees C/min in an argon atmosphere up to combustion/gasification temperatures (850-1150 degrees C), which, is close to the conditions of fluidized bed systems for high ash coal applications. The combustion tests are performed at isothermal conditions under air and oxygen ambience. The reaction regions, peak and burn-out temperatures, mass loss, maximum mass loss rate, and ash content of the different sized coal samples are evaluated. Reactivity index is also calculated to compare the reactivity of various sized coal samples. This research also focused on the main volatile products (H-2, O-2, CO, CH4, CO2) of different sized coal samples on the basis of both their relative intensities and on their relevancy. Activation energy and Arrhenius constant of the coal samples are calculated using volumetric, grain and the random pore models and the results are discussed. The volumetric model showed higher activation energy values as both in the case of air and oxygen gasification. (C) 2017 Elsevier Ltd. All rights reserved.