NOVELTY - Producing (P1) a biomass hydrolysate involves a single hydrolysis step involving: subjecting a slurried biomass to a temperature of 120-200 degrees C, preferably 160-190 degrees C, for a time period of 2 minutes and 8 hours, preferably 20-140 minutes, especially 70-110 minutes, at a mineral acid concentration of 1-15%.    USE - For producing a biomass hydrolysate useful for the production of levulinic acid and formic acid (claimed). The levulinic acid is a starting molecule for the synthesis of esters which is used as fuel additive, and as plasticizers and solvents. The formic acid is used as a preservative and antibacterial agent in livestock feed in the production of leather and in dyeing and finishing of textile; and also used as coagulant in the production of rubber as well as cleaning agent assistant and potential future fuel for fuel cells.    ADVANTAGE - The biomass hydrolysate comprising both levulinic acid and formic acid is produced from biomass containing only one hydrolysis reaction without intermittent cooling and heating or acid dilution. The amount of levulinic acid in the biomass hydrolysate produced by the process is preferably at least 1.1 wt.%, especially at least 2 wt.% or at least 3 wt.%. The amount of formic acid in the biomass hydrolysate produced by the process is preferably at least 0.55 wt.%, especially at least 1 wt.% or at least 1.5 wt.%. The process is advantageous in that any char which is produced does not hamper subsequent isolation of formic acid and levulinic acid from the biomass hydrolysate, or to a lesser extent, as compared to biomass hydrolysates produced by processes known in the art. Also, due to the favorable properties of any char produced by the process, the char does not negatively affect the hydrolysis reaction as much, e.g. it results in little of no clogging of the reactor. The char is isolated from the biomass hydrolysate e.g. by extraction, membrane filtration, or solid-liquid separation. The char is non-sticky and has a favorable particle size which makes it easily to handle.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a biomass hydrolysate obtained by using the process (P1).