One of the major trends in neutron science, in particular in the area of soft matter and biology, is the study of increasingly complex systems, for which the control of environmental parameters (e.g., temperature, pressure, pH, salt concentration, light stimulus etc.) is crucial and the use of complementary characterization techniques is not only helpful, but frequently essential. We have recently made significant progress in the identification of important effects of charges on the phase behaviour of protein solutions, including reentrant condensation, which we propose to study systematically in this project by a combination of spectroscopic techniques traditionally used in the lab and neutron methods. While the materials used in this project are of biological origin, the issues are rather related to the physics of soft condensed matter. We propose to establish simultaneous combined in-situ neutron and optical spectroscopy techniques (e.g. UV/vis, IR, fluorescence, Raman). This will greatly enhance the accuracy with which the state of a fragile biological or soft-matter sample can be defined during neutron spectroscopy experiments.