A combined instrument has been developed for the investigation of plasma deposited or etched surfaces which couples a versatile chemical reaction chamber on-line with a surface analytical system. The plasma can be generated either by microwave (2.45 GHz) or radio frequency (13.56 MHz) excitation, with and without magnetic field assistance. The surface analytical part of the instrument is equipped with monochromatized x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Auxiliary energy or mass spectroscopic techniques can be applied where necessary. All spectroscopies can be performed while the sample is heated or cooled. We report on the general design and the performance of the instrument, as well as first applications in the fields of polymer analysis and bioengineering.