High-pressure processing (HPP), is an innovative food preservation technology that has been developed to meet consumers’ demand for safe, healthy, and minimally processed food. In food systems, the effect of pressure on reaction kinetics can be critical in conditions combining thermal and high-pressure, and in the concept of “Hyperbaric Storage” (HS), a concept that aims not to replace the processing step as in HPP but the cold storage by the application of pressure at milder conditions. At this method, the product is exposed to high pressure for prolonged period time. Yet, the effects of pressure on kinetics are often unknown. Green tea catechins (GTCs) are a group of polyphenols related with flavor, appearance, and known for their health-promoting functionality in plant-based food. Several mechanisms may lead to the degradation of GTCs during processing and storage, making their preservation during storage of significant industrial importance. This study investigates the effect of HS on GTCs degradation kinetics adopting advanced systems (e.g. high hydrostatic pressure system (HHP), in-situ HHP with UV-Vis spectroscopy, and LC-MS analysis). The results provide fundamental information regarding the impact of pressure on degradation kinetics as a function of catechin structure, pH levels, in single and multi-component model systems (such as green tea extract) and relate the degradation to changes in the antioxidant capacity of catechins solutions.