This project investigates chemical reactions in free isolated molecular clusters. The clusters represent a unique environment with rather specific properties for chemistry. The reactive processes of molecules deposited on/in carrying nanometer-sized clusters will be triggered by photons (corresponding to photochemistry) or by electrons - positive ionization (EI) or electron attachment (EA). The latter two processes provide a link to solution phase redox chemistry. We will combine advanced experimental techniques and develop new unique methods. The experiment will be connected with theoretical approaches within a well-established tandem ofteams from JHI and UCT. The project builds on our previous explorations where we have developed a complex toolbox for investigations of molecular clusters. Here we extend the recently developed methods into new fields of application interest: photochemical and redox reactions on ice particles and elementary processes relevant in photocatalytic reactions.