NOVELTY - The method involves grinding lignocellulosic biomass (LB) followed by steam-explosion pre-treatment. The pre-treated LB is filtered and the solid fraction is added into a fermentation deposit (10). Cellulase and beta-glucosidase enzyme are added into the deposit which is inoculated with heat-resistant Kluyveromyces marxianus CECT 10875 culture suspension.    USE - For producing ethanol form lignocellulosic biomass by saccharification and simultaneous fermentation process.    ADVANTAGE - The new strain of Kluyveromyces marxianus CECT 10875, has high heat resistance (claimed), and is capable of fermenting glucose produced by the hydrolysis of cellulose, to ethanol, with improved yield when compared to the conventional original strain. The yeast strain effectively and considerably shortens the treatment time, as it allows the hydrolysis and the fermentation process to take place at 42degreesC which is close to the optimum temperature for cellulolytic complex. The simultaneous saccharification and fermentation process effectively utilizes the new strain. The particle size of the ground lignocellulosic biomass material mainly containing cellulose, such as forestry and agricultural residues, paper paste, lignocellulosic crop biomass and organic fraction of domestic waste, required for the pre-treatment is larger than the conventional size. Hence, the energy cost associated to grinding of biomass, is effectively reduced. The steam explosion treatment which increases the digestibility of cellulose to enzymatic hydrolyses, is a novel method. The increase in digestibility is directly related to increase in the available surface area (ASA) of cellulose fiber, which facilitates the eventual enzymatic attack by cellulases. The increase of ASA is a result of partial or total elimination of hemicellulose and lignin.    DETAILED DESCRIPTION - Production of ethanol from lignocellulosic biomass (LB), involves grinding LB subjecting to steam explosion pre-treatment, and maintaining at 1-3 MPa and at 190-230degreesC, for 1-10 minutes, depending on the type of material used and later provoking rapid de-pressurization. The liquid and solid fractions in the pre-treated material, are separated by filtration, and the solid fraction is introduced in a fermentation deposit. The deposit is added with a cellulase in a concentration of 15 UFP/g of cellulose and 12.6 International Units of beta-glucosidase enzyme. The deposit is then inoculated with a culture suspension of a heat-resistant yeast Kluyveromyces marxianus CECT 10875, and the mixture is subjected to shaking for 72 hours at 42 degrees Centigrade. After completion of the reaction, the concentration of ethanol and residual sugars in the mixture are determined.    DESCRIPTION OF DRAWING(S) - The figure shows a diagram of the procedure for the production of ethanol from lignocellulosic biomass.    Fermentation deposit (10)