The combustion characteristics of microalgae, brown coal and their blends under O-2/N-2 and O-2/CO2 atmospheres were studied using thermogravimetry. In microalgae combustion, two peaks at 265 and 485 degrees C were attributable to combustion of protein and carbohydrate with lipid, respectively. The DIG profile of coal showed one peak with maximum mass loss rate at 360 degrees C. Replacement of N-2 by CO2 delayed the combustion of coal and microalgae. The increase in O-2 concentration did not show any effect on combustion of protein at the first stage of microalgae combustion. However, between 400 and 600 degrees C, with the increase of O-2 partial pressure the mass loss rate of microalgae increased and TG and DTG curves of brown coal combustion shifted to lower temperature zone. The lowest and highest activation energy values were obtained for coal and microalgae, respectively. With increased microalgae/coal ratio in the blends, the activation energy increased due to synergy effect. (C) 2013 Elsevier Ltd. All rights reserved.