Butanol is considered as a potential fuel due to several advantage over ethanol. However, it is still of urgent demand to identify better feedstock, which is more renewable and cost-effective, for the production of bio-butanol. Microalgae can mitigate CO2 emission and convert CO2 into biomass abundant in carbohydrates, and thus appear as emerging third-generation feedstock for fermentation. In this study, an isolated microalga Chlorella vulgaris was cultivated photoautotrophically and the biomass was then harvested for the use in butanol fermentation with a Clostridium acetobutylicum strain via acetone-butanol-ethanol (ABE) fermentation. The results show that 3.37 g L-1 of butanol was produced from 111g of acid-pretreated biomass of C. vulgaris. This demonstrates the potential of using microalgal feedstock for fermentative butanol production. The results also suggest that to improve hydrolysis efficiency of C. vulgaris, higher concentration of sulfuric acid (>2%) should be used.