The book provides the first comprehensive description of experiences gained at the Ketzin pilot site located in the Federal State of Brandenburg, Germany. The Ketzin pilot site has been the first ever European on-shore CO2 storage project and is still the only storage project in Germany. It is a pure research and development project and limited by legal regulations to a maximum amount of stored CO2 of 100 000 t. The reservoir target horizon is a deep saline formation of upper Triassic age in an anticline structure above a salt pillow within the Northeast German Basin. By this the Ketzin pilot site shares fundamental geologic characteristics to be expected for other CO2 storage sites in Germany and worldwide. Besides operational aspects the focus at the Ketzin pilot site is on monitoring and modelling the subsurface behavior of the injected CO2. The applied monitoring programme is among the most comprehensive worldwide so far applied to CO2 storage sites.