Analytical developments over the last few decades have significantly improved the capabilities to analyse hydrogen and oxygen isotopes in various environmental materials (e.g., specific organic compounds from algae and plants, ambient water, leaf water as well as proxy materials in climatic archives). In conjunction with the outstanding possibility to investigate water isotope compositions by isotope modelling, these studies promise great potential to furthering our understanding of present-day hydrological processes, biosynthetic effects and paleo-climatological conditions. To deliver a state-of-the-art overview of ongoing activities, we invite contributions related to the development, calibration, and application of water isotope analyses as well as modelling of the hydrological cycle.