Anaerobic fermentation processes are generally limited by low cell concentrations that eventually results in low volumetric productivity. The aim of the present study was to establish a continuous fermentation process for a metabolically engineered C. acetobutylicum strain which can result in high butanol and ABE productivities.The maximum obtained ABE and butanol productivities were 15.7 and 7.9 g l1 h1 respectively. The merit of this work is that this is the first report on continuous fermentation with cell recycling using a metabolically engineered C. acetobutylicum. The butanol and ABE productivities obtained during present study is the highest reported productivities obtained during continuous acetonebutanolethanol fermentation by any of the reported strains.