This project aims at the optimization of chemical reactions by using online analytical and chemometric methods. The experiments are carried out in a fully automated chemical reactor (1 liter). The host computer controls the standard process variables such as mixture temperature, jacket temperature, pressure, added mass, pH, … In addition, it receives in real-time the online analytical data (Raman, FT-IR and mass spectrometry). These data are then processed by chemometric methods without calibration. These methods reveal reaction events such as start points of the main and the secondary reaction, end points of these reac-tions and changes in physical quantities. As a model reaction, the aldol condensation between acetone and benzalde-hyde was chosen. This reaction fulfills the following criteria: suitable reac-tion time, formation of two reaction products and affordable starting mate-rial. In parallel to the online measurements, the reaction is followed by con-ventional chemical analysis (liquid chromatography, NMR).