Method for producing furfural comprising the steps of - providing an aqueous feed mixture comprising: (i) one or more substances selected from the group consisting of xylose, oligosaccharides comprising xylose units and polysaccharides comprising xylose units (ii) methanesulfonic acid (iii) one or more salts wherein the total concentration of (iii) said one or more salts is in the range of from 0.5 wt.-% to 20 wt.-% based on the total weight of said aqueous feed mixture, - contacting said aqueous feed mixture with an extraction liquid comprising one or more organic solvents, wherein said one or more solvents - have a higher solubility for furfural than said aqueous feed mixture and - are selected so that when said aqueous feed mixture is contacted with said extraction liquid two separate liquid phases are formed, wherein in a first liquid phase the concentration of water is higher than the concentration of said organic solvents and in a second liquid phase the concentration of said organic solvents is higher than the concentration of water - subjecting said aqueous feed mixture while contacted with said extraction liquid to a thermal treatment so that said one or more substances selected from the group consisting of xylose, oligosaccharides comprising xylose units and polysaccharides comprising xylose units are reacted to furfural which is extracted from said aqueous feed mixture into said extraction liquid. - providing an aqueous feed mixture comprising: (i) one or more substances selected from the group consisting of xylose, oligosaccharides comprising xylose units and polysaccharides comprising xylose units (ii) methanesulfonic acid (iii) one or more salts wherein the total concentration of (iii) said one or more salts is in the range of from 0.5 wt.-% to 20 wt.-% based on the total weight of said aqueous feed mixture, (i) one or more substances selected from the group consisting of xylose, oligosaccharides comprising xylose units and polysaccharides comprising xylose units (ii) methanesulfonic acid (iii) one or more salts wherein the total concentration of (iii) said one or more salts is in the range of from 0.5 wt.-% to 20 wt.-% based on the total weight of said aqueous feed mixture, - contacting said aqueous feed mixture with an extraction liquid comprising one or more organic solvents, wherein said one or more solvents - have a higher solubility for furfural than said aqueous feed mixture and - are selected so that when said aqueous feed mixture is contacted with said extraction liquid two separate liquid phases are formed, wherein in a first liquid phase the concentration of water is higher than the concentration of said organic solvents and in a second liquid phase the concentration of said organic solvents is higher than the concentration of water - have a higher solubility for furfural than said aqueous feed mixture and - are selected so that when said aqueous feed mixture is contacted with said extraction liquid two separate liquid phases are formed, wherein in a first liquid phase the concentration of water is higher than the concentration of said organic solvents and in a second liquid phase the concentration of said organic solvents is higher than the concentration of water - subjecting said aqueous feed mixture while contacted with said extraction liquid to a thermal treatment so that said one or more substances selected from the group consisting of xylose, oligosaccharides comprising xylose units and polysaccharides comprising xylose units are reacted to furfural which is extracted from said aqueous feed mixture into said extraction liquid.