The invention relates to an apparatus and a process for the preparation of anhydrous or substantially anhydrous formic acid. This apparatus is constructed partly or entirely of substantially zirconium-free materials. The extractant employed is a liquid of the general formula I ##STR00001## where the radicals R.sup.1 and R.sup.2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R.sup.1 and R.sup.2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R.sup.3 is hydrogen or a C.sub.1 C.sub.4-alkyl group. The apparatus has a synthesis reactor (6), a hydrolysis reactor (1), three distillation devices (2,4,5) and an extraction device (3).