A process for the preparation of a dicarboxylic acid of the formula (I) —H—OOC-(n-C4Hx)—COO—H  (I)where x is 6 or 8, starting from acrylic acid, which comprises a) reacting a dicarboxylic acid diester of the formula (II) R1—OOC-(n-C4Hx)—COO—R2  (II)where x is 6 or 8, and R1 and R2, independently of one another, are C1-, C2-, C3- or C4-alkyl, aryl or heteroaryl and may be identical to or different from one another, with acrylic acid to give a dicarboxylic acid of the formula (I) and a mixture of acrylic acid esters of the formulae C2H3—COOR1 and C2H3—COOR2, where R1 and R2 are as defined above, b) separating the dicarboxylic acid of the formula (I) obtained in step a) from the reaction mixture obtained in step a), c) dimerizing the C2H3—COOR1, C2H3—COOR2 or mixture thereof obtained in step a) to give an n-butenedicarboxylic acid diester, and d) cleaving the dicarboxylic acid diester obtained in step c) into the corresponding dicarboxylic acid of the formula (I).