A method of cooling hot gases

Gas coolers in which hot gasses are brought into contact with a moving cooling liquid film are used for cooling hot gasses and thus for preventing the formation of condensation cores. In a process for cooling hot gaseous reaction products from gas phase reactions for preparing glyoxal of compounds of general formula (I): H2C=C(R )-C(R )=O, in which R is hydrogen or methyl and R is hydrogen or OH, in particular acrolein, methacrolein, acrylic acid and methacrylic acid, hot gaseous reaction products are brought into contact with a cooling liquid in a gas cooler, and the cooling liquid is present in the form of a moving liquid film.