Coffee is the second most valuable commodity exported by developing countries - second to crude oil. The coffee roasting process is a significant factor in determining coffee flavor and is controlled by a roast master, who takes especially sensory and physical parameters like weight loss, smell or bean color into account. For an improvement batch consistency these parameters are not useful. Coffee roasting is a very complex process being influenced by the used beans, roaster technique and various conditions.  Therefore an online measurement of the gas phase during roasting serves a high variety of different parameters. The aim is to obtain an understanding of the roasting process and to achieve a model for different coffee roasters and roasting conditions. Due to the high complexity of the investigated matrix, especially soft photoionization techniques such as SPI (single photon ionization) as well as REMPI (resonance enhanced multiphoton ionization) will be used combined with the fast and reliable TOF-MS (time-of-flight mass spectrometry) technology to achieve time resolved information of the roasting process.