Global warming is thought to be caused mainly by the emission of carbon dioxide (CO2), with thermoelectric power plants being responsible for about 7% of global CO2 emissions. Microalgae can reduce CO2 emissions from thermoelectric power plants, but for this use, they must be resistant to the mixture of gases produced by the power plants. We isolated the microalgae Scenedesmus obliquus and Chlorella kessleri from the waste treatment ponds of the Presidente Medici coal fired thermoelectric power plant in the Southernmost Brazilian state of Rio Grande do Sul and investigated their growth characteristics when exposed to different concentrations of CO2. When cultivated with 6% and 12% CO2, C. kessleri showed a high maximum specific growth rate (lambda(max)) of 0.267/day, with a maximum biomass productivity (P-max) of 0.087 g/L/day at 6% CO2. For S. obliquus, the highest maximum dry weight biomass value was 1.14 g/L with 12% CO2. We also found that these two microalgae also grew well when the culture medium contained up to 18% CO2, indicating that they have potential for biofixation of CO2 in thermoelectric power plants. (C) 2007 Elsevier Ltd. All rights reserved.