With a method or a device for producing 1,2-dichloroethane or ethylene (di)chloride (EDC) with the use of a circulating reaction medium and a catalyst, whereby ethylene and chlorine are supplied to the reaction medium, the catalytic chlorination of ethylene is achieved in a manner that is particularly gentle to the product by introducing the ethylene or chlorine gas into the reaction medium via microporous gas diffuser elements for producing gas bubbles with a diameter of 0.3 to 3 mm.