A process for the preparation, of (pyrimidin-2-yl)methyl ketones of the general formula (I), ##STR00001## in which R.sup.1 is in each case a C.sub.1-10-alkyl group, a C.sub.3-8-cycloalkyl group, an allyl group or an aryl-C.sub.1-4-alkyl group, and R.sup.2 is a C.sub.1-10-alkyl group or aryl group. For this, a malondiimidate of the general formula (II), ##STR00002## in which R.sup.1 has the meaning given above, is reacted with a .beta.-keto ester of the general formula (III), ##STR00003## in which R.sup.2 has the meaning given above, and R.sup.3 is a C.sub.1-10-alkyl group. The compounds which can be prepared according to the invention are intermediates for the synthesis of agrochemical active ingredients.