Abstract: Studies on direct use of palm oil mill effluent (POME) as fermentation medium for acetone-butanol-ethanol (ABE) production by Clostridium acetobutylicum NCIMB 13357 and C. saccharoperbutylacetonicum N1-4 have been carried out in batch culture system. Investigations were carried out on the effect of concentration of sedimented POME, the effect of initial culture pH and the use of immobilized cells for ABE production. It was found that C. acetobutylicum NCIMB13357 grown in 90% sedimented POME with initial pH 5.8 produced highest total ABE (4 g L-1). However, butanol production was maximum (1.82 gL-1) in the culture with the initial pH of 6.0. Results obtained from these experiment with immobilized cells of C. saccharoperbutylacetonicum N1-4 indicated that ABE production from POME could be improved when high concentrations of cells at solventogenic growth phase were used.