Eight Clostridium acetobutylicum strains were examined for α-amylase and strains B-591, B-594 and P-262 had the highest activities. Defibered-sweet-potato-slurry (DSPS), containing 39.7g starch l - 1 , supplemented with potassium phosphate (1.0gl - 1 ), cysteine-HCl (5.0gl - 1 ), the antifoam (polypropylene glycol, 0.1mgml - 1 ), was used as continuous feedstock (FS) to a multistage bioreactor system for acetone-ethanol-butanol (AEB) fermentation. The system consisted of four columns (three vertical and one near horizontal) packed with beads containing immobilized cells of C. acetobutylicum P-262. When DSPS was pumped into the bioreactor system, at a flow rate of 2.36mlmin - 1 , the effluent had 7.73g solvents l - 1 (1.56, acetone; 0.65, ethanol; 5.52g, butanol) and no starch. Productivity of total solvents synthesized during continuous operation were 1.0gl - 1 h - 1 and 19.5% yield compared to 0.12gl - 1 h - 1 with 29% yield using the batch system. We propose using DSPS for AEB fermentation in a continuous mode with immobilized P-262 cells that are active amylase producers which will lead to cost reduction compared to the batch system.