A purified acid composition including 2,5-furandicarboxylic acid is prepared in a process, including oxidizing a feedstock containing 5-alkoxymethylfurfural to an oxidation product including 2,5-furandicarboxylic acid (FDCA) and 2-formyl-furan-5-carboxylic acid (FFCA), and esters of FDCA and, optionally, esters of FFCA; hydrolyzing the at least part of the oxidation product in the presence of water, thereby hydrolyzing at least esters of FDCA and, optionally, esters of FFCA to obtain an aqueous solution of an acid composition including FDCA, FFCA and ester of FDCA in an amount below the amount of ester of FDCA in the solution of the oxidation product; contacting at least part of the solution of the acid composition with hydrogen in the presence of a hydrogenation catalyst to hydrogenate FFCA to hydrogenation products, yielding a hydrogenated solution; and separating at least a portion of the FDCA from at least part of the hydrogenated solution by crystallization.