Butanol is a virtually promising bio fuel of our future imputing to its higher blending ratios in petrol and diesel without any retrofitting in IC engines. Biobutanol was produced from Acetone Butanol and Ethanol (ABE) fermentation of 5% ortho phosphoric acid pretreated paddy straw biomass using Clostridium acetobutylicum ATCC 824 strain. ABE fermentation was a zymolysis process of Clostridium bacteria, the anaerobic breakdown of sugars into alcohols in which the solvents formed were a result of two different phases of acidogenesis and solventogenesis. The optimal pH for maximal conversion of sugars into alcoholic compounds was . | A probe into the biphasic nature of the acetone butanol ethanol ABE fermentation by clostridium acetobutylicum ATCC 824