Gediz lignite was pyrolyzed in a thermobalance apparatus at atmospheric pressure in this study. Effects of heating rate and particle size on the pyrolysis kinetics were examined. Experiments were conducted at nonisothermal conditions with a heating rate range of 10 to 90 K/min under an argon atmosphere in the pyrolysis temperature interval of 298 to 1173 K. Two different particle size ranges were tested: 595 > D-p > 297 and 53 > D-p > 44 Am. Average relative volatile matter yields were calculated as 40.6 and 39.0% of the total volatile matter yields from 678 to 777 K for the linear segments of the thermogravimetric (TG) curves of the larger and smaller size particles, respectively. TG data were analyzed by a reaction rate model assuming first-order kinetics, and lower apparent activation energies were calculated at higher heating rates. Minimum apparent activation energy was obtained as 9.05 kJ/mol at the heating rate value of 90 K/min with 53 > Dp > 44 Am size particles.