The Green Chamber is an ultra high vacuum chamber equipped with a scanning tunnelling microscope (STM), a mass spectrometer and x-ray photoelectron spectroscopy (XPS) equipment. The STM (Aarhus model) can run at room temperature or can be cooled to liquid nitrogen temperatures. The manipulator can also be cooled using liquid nitrogen, allowing for temperature programmed desorption experiments, with the mass spectrometer recording masses up to 100 m/z. In combination with an atomic hydrogen doser and a small heater for dosing solid material, the Green Chamber allows for a wide range of surface analysis experiments.