Provided herein is a process for preparing furan-2,5-dicarboxylic acid. The process includes the following steps: (A-1) preparing a starting mixture comprising one, two or more carbohydrate compounds selected from the group consisting of: hexoses, oligosaccharides comprising hexose units, and polysaccharides including hexose units, and as a solvent or as a co-solvent for the carbohydrate compounds an amount of one or more carboxylic acid esters of a formula (II) and (A-2) subjecting the starting mixture to reaction conditions so that at least one of the one, two or more carbohydrate compounds reacts, and a fraction of the amount of one or more carboxylic acid esters of formula (II) is hydrolyzed, resulting in a mixture including 5-(hydroxymethyl)furfural and/or the one or more HMF esters of a formula (I), one or more carboxylic acids of a formula (III) and a remaining fraction of the amount of one or more carboxylic acid esters of formula (II).