A process for preparing formic acid by reaction of carbon dioxide (1) with hydrogen (2) in a hydrogenation reactor (I) in the presence of a catalyst comprising an element of group 8, 9 or 10 of the Periodic Table, a tertiary amine comprising at least 12 carbon atoms per molecule and a polar solvent comprising one or more monoalcohols selected from among methanol, ethanol, propanols and butanols, to form formic acid/amine adducts as intermediates which are subsequently thermally dissociated, where the work-up of the output (3) from the hydrogenation reactor (I) is carried out by addition of water so as to increase the distribution coefficient of the catalyst between the upper phase (4) and the lower phase.