The present invention relates to an improved method of second generation ethanol production from a lignocellulosic biomass. The process comprises subjecting a slurry of pre-treated lignocellulosic biomass comprising C5 and C6 sugars in a fermentor; preferentially fermenting mainly C5 sugars by incubating the pretreated lignocellulosic biomass of step (i) with first cellulase enzyme, co-fermenting microorganism, nutrient in the fermentor at 30-37° C. for a period of 16 to 24 hours; adding second cellulase enzyme to the fermentation broth of step (ii) and increasing the temperature to 45-55° C. for hydrolysis; allowing the fermentation broth of step (iii) to cool to a temperature of 35-38° C.; and preferentially fermenting C6 sugars by incubating the broth of step (iv) with a second dose of co-fermenting microorganism for a period of 6-8 hours to obtain ethanol. The process results in high ethanol productivity in shortest duration of time.