Recent advances in spacecraft explorations have revealed evidence for past (or current) presence of liquid water on multiple Solar System bodies, including Mars, icy satellites, and volatile-rich dwarf planets. To further understand the formation, evolution, and habitability of these aquaplanets in the Solar System, knowledge of physico-chemical processes that characterize aqueous environments becomes critical. These processes include water-rock reactions, hydrological and geochemical cycles, photochemistry, and tectonics. These processes generate both oxidants and reductants and transport them in hydrospheres, creating bioavailable chemical disequilibria. This session covers topics relevant to physico-chemical processes on aquaplanets (including Earth, Mars, water-altered asteroids, and ocean worlds), e.g., geochemical processes on terrestrial planets and icy bodies, planetary hydrology, icy tectonics, and planetary organic chemistry. This session also welcomes observational studies of geochemical signatures of aqueous environments on Solar System bodies using spacecraft, rovers, and telescopes.