In a method for cooling of process gas between catalytic layers or beds in a sulfuric acid plant, in which sulfuric acid is produced from feed gases containing sulfurous components like SO2, H2S, CS2 and COS or liquid feeds like molten sulfur or spent sulfuric acid, one or more boilers, especially water tube boilers, are used instead of conventional steam superheaters to cool the process gas between the catalytic beds in the SO2 converter of the plant. Thereby a less complicated and more cost efficient heat exchanger layout is obtained.