Process for the production of sugars from biomass including at least one polysaccharide which comprises putting a biomass in contact with an aqueous solution of at least one organic acid having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, the pH of said aqueous solution being ranging from 0.6 to 1.6, preferably ranging from 0.9 to 1.3. The sugars thus obtained can be advantageously used as carbon sources in fermentation processes for the production of alcohols (e.g., ethanol, butanol), diols (e.g., 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol), lipids, or other intermediates or products. Said alcohols, diols, lipids, or other intermediates or products, can be advantageously used in the chemical industry or in the formulation of fuels for motor vehicles. Said alcohols and said diols can also be advantageously used in the bio-butadiene production.