This work is all about producing bioethanol as an alternative fuel from lignocellulosic biomass. Lignocellulosic biomass used here is saccharum spontaneum; a hardy weed prevalent in all over india and subtropical climate with little or no economic value. Microorganism used here is Pichia stipitis a yeast that can degrade both hexoses and pentoses efficiently. This work is novel in its approach of using a different substrate and an efficient microbe.