A thermal separation process between a gas ascending in a separating column and a liquid descending in the separating column, which comprise (meth)acrylic monomers, wherein the separating column comprises a sequence of crossflow mass transfer trays, the crossflow mass transfer trays of which have passage orifices for the ascending gas in crossflow direction both in front of and beyond a downcomer for the descending liquid, and such crossflow mass transfer trays and one such crossflow mass transfer tray in a sequence of crossflow mass transfer trays present in a separating column.