The present invention is directed to a cleaning device for process gases of a reflow soldering system that includes a plurality of cleaning chambers. The plurality of cleaning chambers contain a cleaning liquid for the process gas, where each of the cleaning chambers is adapted to be flown through via a supply line for the contaminated process gas and via a discharge line for the cleaned gas. The cleaning chambers also include a plurality of cleaning walls along which the cleaning liquid is flown for take-up of impurities in the process gas into the cleaning liquid. A plurality of the deposition walls is provided, where at least one of the deposition walls also forms an outer wall of the cleaning device.