The project TRANSENERGY – Transboundary Geothermal Energy Resources of Slovenia, Austria, Hungary and Slovakia aims is to provide implementation tools based on a firm geoscientific basis for enhanced and sustainable use of geothermal resources.The project addresses the key problem of using natural resources that are shared by different countries in a sustainable way. Natural resources, such as geothermal energy whose main carrying medium are deep groundwaters along regional flow paths are strongly linked to geological structures that do not stop at state borders. Therefore only a transboundary approach and the establishment of a joint, multi-national management system may handle the assessment of geothermal energy and conditions of its sustainable use.The enhanced use of geothermal energy contributes to one of the main goals of the European Unions energy policy of increasing the proportion of renewable energy resources to 12 % within the total energy consumption by 2010 and to 20% by 2020 (2001/77/EC). The increasing use of geothermal energy also reduces the emission of carbon dioxide, as its utilisation produces zero greenhouse gas emission, thus it is a major step to implement the Kyoto Protocol (target of 8% CO2 reduction by 2012) and to mitigate unfavourable effects of climate changes articulated in the European Climate Change Programs (ECCP I and II) and related policies and regulations. Achievements: The enhanced use of renewable energies is in the focus of integrated climate and energy policies. The Pannonian basin has outstanding potentials of geothermal energy due to the favourable geological conditions, which is shared by Central European countries. The main carrying medium of geothermal energy is thermal groundwater, flowing along regional flow paths which are strongly linked to geological structures that do not stop at state borders. TRANSENERGY addresses a transboundary approach and the establishment of a harmonized, multi-national management system for the joint assessment of geothermal potential of the region. The project started in April 2010 and finished in September 2013. The project website (http://transenergy-eu.geologie.ac.at) informs about main events and results which can be downloaded. The project results and progress was supervised and approved by an External Evaluation Board composed of national and international experts. The results include the database of authorities dealing with geothermal energy utilization, database of 172 current users and utilization parameters wich are visualized on 12 utilization maps. Summary reports overviewed the utilization aspects, waste water treatment, monitoring practices, exploited geothermal aquifers and their further potentials, as well as the EU and national legislations related to geothermal energy. A core output report summarized the methodology for joint (thermal) groundwater and geothermal resources assessment. Geological, hydrogeological and geothermal data used for the geoscientific models were collected, harmonized and uploaded into a multilingual geothermal database (MS-ACCESS), containing data from 1686 boreholes from the 4 countries organized into 438 parameters types. Geological, hydrogeological and geothermal models were established for the entire project area,as well as for 5 selected cross-border pilot areas showing in details the geoscientific characters and vulnerability of the investigated transboundary hydrogeothermal systems. Steday state models described the regional thermal water flow systems in 3D, quantified the major cross-border thermal water budgets, provided heat base calculations for the pilot regions, and characterized the present state of the geothermal reservoirs. Scenario modelling provided information about the possible limitations in thermal water utility, the need of protection, and described the geothermal exploitation capacity of the regions with indications on priorities in thermal water use. The results of the models are available as interactive web-map services via the project portal, which also encompasses data from selected boreholes and their parameters as public database, as well as the utilization maps. Final recommendation are summarized in a Strategy Paper.