Typical methods for monitoring cultivation processes are offline analyses like cell counting, measurement of various substrates and products (e. g. glucose or lactate) as well as the online monitoring of several physical process parameters (temperature, pH-value or the concentration of dissolved oxygen). To improve cell cultivations detailed information about important analytes should be available online. Therefore new monitoring methods need to be established, preferably as in-situ methods to minimize the risk of contamination. Two different in-situ online-methods were used to monitor cultivations: In-situ microscopy and 2D fluorescence spectroscopy. Therefore CHO-K1 cells (provided by University of Bielefeld) were cultivated in a complex culture medium (TC 42, TeutoCell, Bielefeld, Germany) using a 2.5 L stainless steel reactor with a work volume of 2 L. A total of three cultivation runs were conducted.