This paper is describing a new tool, based on optical emission spectroscopy, for the detection and the recording of short and long term variations in thermal spraying applications. By using an online analysis of the emitted process spectra the user is enabled to get direct access to the running process and the resulting coating quality. It has been proved in numerous investigations that all relevant process parameters, which are significant for the layer forming and its properties, can be separated and detected. Furthermore, first investigations are showing that all results obtained for plasma spraying applications can be transferred to wire arc, flame and high velocity oxygen fuel spraying. Paper text in German.