**Abstract**

Ethanol production from agricultural products mainly corn, wheat, sweat potato and residue are gaining importance and requires an industrially viable novel technology namely simultaneous saccharification and fermentation process. This process has an advantage of carrying out saccharification using enzyme and fermentation using yeast in a single fermenter. The investment cost for industrial ethanol production using cheap agricultural residues can be well achieved using SSF process. The success of SSF process greatly depends upon the pretreatment methods using different enzymes to break the complex carbohydrates to simple sugars. Optimization of key process variables is essential to maximize the ethanol yield from suitable substrates. The key process variables affecting the SSF process are pH, temperature, fermentation time, enzyme concentration and substrate concentration. The medium components are to be screened for effective nitrogen, potassium and phosphorous sources to increase the ethanol yield.

**Keywords:** simultaneous saccharification and fermentation, pretreatment, enzymes, ethanol, yeast pH and temperature
