Background Emission inventory is a key component of sound environmental management and is necessary for the planning, implementation and evaluation of environmental policy at the local, regional and national levels. Emission inventory also plays a crucial role in international conventions such as the Convention on Long-range Transboundary Air Pollution (CLRTAP) and the United Nations Convention on Climate Change (UNFCCC). In that regard, a great effort has been made in recent years to find ways to support developing countries and countries in transition to create or upgrade emission inventory systems. As part of the CLRTAP and UNFCCC conventions, Croatia is obliged to report on its emissions in an international standardised manner. However, before the LIFE project, the country was still not providing appropriate information to UNFCCC or the European emission inventory system CORINAIR. After four years, the national emission inventory system of Croatia (KEO) was not functioning as it should. A very small amount of data, generally of poor quality, had been collected. In addition, KEO was not used for environmental management purposes or national emissions estimates. Objectives The project’s purpose was to establish an integrated, cost effective emission inventory system that would satisfy domestic needs and that would enable high quality, timely, transparent and consistent international reporting. Results The project team upgraded the National Emission Inventory System (NEIS) in Croatia. The new NEIS comprises: · The revised and updated “Cadastre of Emissions to Environment” (KEO), i.e. the web-based software collecting information on emission sources; · The “National Emission Database” (CollectER), i.e. the software storing information collected via KEO (processed or not by the software EstimatER or COPERT); and · The “Reporting System” (ReportER), i.e. the software using data stored in CollectER to create standardised reports (UNFCCC, CLRTAP, CORINAIR, PRTR and national agencies’ format). The different components of the new NEIS have been successfully tested. The beneficiary produced general and sectorial guidelines to help users reporting in the KEO. In addition, they drafted a by-law, which is in the last stage of revision before official approval by the Government and that will provide a legal framework for reporting activities. The project team did also some preparatory work for the quality assurance of the new NEIS and carried out numerous dissemination activities. Overall, the project led to a significant increase in the capacity of Croatia for sound environmental management: the new NEIS will enable the country to formulate, monitor and evaluate sustainable environmental policies at the local and national level, and report to international organisations in a standard manner. In addition, as the new NEIS will be supported by a by-law and should be outsourced to the Croatian Environmental Protection Agency in the near future, the project results are likely to be sustainable.