A proposal of hierarchic characterization of the Spanish rivers for their classification in accordance to the Water Framework Directive of the European UnionRiver classification has an important role in the management and conservation of fluvial ecosystems, and represents a first step in the implementation of the European Water Framework Directive.According to the development of scientific knowledge in fluvial ecology and computer techniques for the spatial characterisation of hydrographic regions, different systems of taxonomic and regional classification have been proposed, finally integrating the river within the context of its watershed.In this paper, the historical evolution of river characterisation schemes is reviewed, and a hierarchical characterisation approach is proposed according to different scales, biogeographic provinces, watershed, river segments, and river reaches attending to the main factors determining biological communities in river ecosystems.This proposed characterisation scheme is prepared to be used by GIS, from maps and fieldwork at the reach scale.It is an open-tree characterisation method, where new information can be incorporated and some of the criteria can be further detailed, adding new characteristics and subclasses at the different scales being considered, allowing for the development of a classification scheme based on hydrological and ecological criteria in common for the whole Spanish territory.It includes all the mandatory factors for river classification according to the Water Framework Directive, as well as some of the hydromorphological elements established by the Directive for identifying the ecological status of the different fluvial stretches, and for proposing management (restoration) and conservation measures.