In this study, Scenedesmus obliquus SJTU-3 and Chlorella pyrenoidosa SJTU-2 were cultivated with 0.03%, 5%, 10%, 20%, 30%, 50% CO2. The two microalgae could grow at 50% CO2 (>0.69 g L-1) and grew well (>1.22 g L-1) under CO2 concentrations ranging from 5% to 20%. Both of the two examined microalgae showed best growth potential at 10% CO2. The maximum biomass concentration and CO2 biofixation rate were 1.84 g L-1 and 0.288 g L-1 d(-1) for S. obliquus SJTU-3 and 1.55 g L-1 and 0.260 g L-1 d(-1) for C. pyrenoidosa SJTU-2, respectively. The main fatty acid compositions of the two examined microalgae were fatty acids with C-16-C-18 (>94%) under different CO2 levels. High CO2 levels (30-50%) were favorable for the accumulation of total lipids and polyunsaturated fatty acids. The present results suggested that the two microalgae be appropriate for mitigating CO2 in the flue gases and biodiesel production. (C) 2010 Elsevier Ltd. All rights reserved.