A setup for in situ mass spectrometric reaction monitoring of gas phase mediated reactions is presented. Important constructive parameters for a reaction chamber for the investigation of atmospheric corrosion processes is discussed. The presented cell is especially well suited for atmospheric corrosion studies but it can easily be modified to be applicable in other fields of research as well. The atmospheric corrosion of electrolytically deposited zinc surfaces on steel during wet and drycycles is investigated as a model reaction. Corrosion rates as well as current densities during the first wet and dry cycle are calculated and discussed. Complementary scanning Kelvin probe (SKP) measurements are performed to show the electrochemical changes occurring at the metal/airinterface throughout the corrosion process. Contact potential difference versus distance measurements performed in advance to determine the maximum measurement distance, which allows investigating rough salt loaded sample surfaces via SKP surface scans.