Drainage networks and associated drainage basins form complex functional entities not only for hydrological processes but also for environmental processes at large. This has been recognised in recent European legislation such as the Water Framework Directive (WFD). In order to study the underlying processes and cause-effect relationships at regional to European scales, comprehensive digital data of river networks, drainage basins (catchments) and their characteristics are required. JRC's Catchment Characterisation and Modelling (CCM) activity responded to this need through the development of a pan-European database of river networks and catchments. Version 1.0 of CCM has been published in 2003. In July 2007 an geographically extended and substantially improved CCM Version 2.0 has been released. The current Version 2.1 of July 2008 is an update of version 2.0. It includes the correction of noted errors as well additional functionality. A detailed report on the development of CCM 2.0 as well Release Notes for CCM 2.1 are provided below.