The invention discloses a continuous fermentation process for production of acetone, butanol and ethanol using a local aerotolerant isolate, Clostridium acetobutylicum YM1, by conversion of sugars that are liberated from the pretreatment of de-oiled rice bran (DRB). In this process, DRB was utilized as a cheap, sustainable and available substrate. The process involves the pretreatment of DRB as a cheap and available feedstock to generate fermentable sugars. The DRB hydrolysate was used as a medium in a continuous fermentation by C. acetobutylicum YM1 with a dilution rate of 0.02 h-1 and the total solvent titer obtained was 12.42 g/L with butanol titer of 6.87 g/L, respectively, with a solvent productivity of 0.248 g/L.h. Thus, this process allows competitive production of butanol by decreasing the overall production cost.