The Parliament of the European Union has issued stricter emission standards (Euro 4 and 5) for HD diesel engines for the years 2005 and 2008. Compared to current limits an emissions reduction of 60 % for nitrogen oxides and of 80 % for particulate matter will be required. After comparing and testing various technical options the European manufacturers of HD commercial vehicles have agreed on one method for meeting these standards: the 'selective catalytic reduction' (SCR technology), which converts nitrogen oxides into innocuous nitrogen and water in the presence of a reducing agent. The European automobile industry has also agreed on one reducing agent: an aqueous solution of urea, which shall be distributed under the trade name 'AdBlue'. The main reason for this decision of the HD commercial vehicle industry was the fact that the SCR/urea technology appears to be the only method which enables the necessary decrease of exhaust emissions while maintaining engine optimization with regard to performance and fuel economy. Furthermore this method can be applied to all engines. The present report describes the production, properties and environmental impact of urea as well as of its aqueous solution. Since the solution is corrosive, certain materials are required for its handling. Product quality and properties of AdBlue are defined in the DIN standard 70070, which should form the basis for a later EN or ISO standard. According to a survey of the Association of the Automobile Industry (VDA), the annual demand for AdBlue for the use in HD commercial vehicles is estimated to increase from initially 500 t to over 2.5 million t in the year 2012. The cost of AdBlue is mainly determined by the costs of energy and raw materials in the production of urea, also by the costs for distribution; the latter depend on the means of distribution and the investments probably required at the service stations. The present report describes the activities of national and international committees working on the introduction of the SCR/urea technology. Beginning in the year 2004, the European automobile industry plans to equip their HD trucks with the SCR converters. It is proposed that the supply of these vehicles with AdBlue will be accomplished in three phases: initially by filling stations of larger fleet owners, followed by filling stations along magistrale routes in Europe and finally also by public filling stations in a balanced distribution in Europe. The automobile industry assumes that AdBlue will be distributed through a separate tanking system. Mineral oil industry and trade will have to decide whether they will offer the reducing agent required for the SCR/urea technology, at their service stations, and whether they will invest in the necessary infrastructure of additional tanks, piping, pumps and filling nozzles, or whether they prefer to supply AdBlue in mobile containers, from which the truck drivers can fill up their AdBlue tanks. This report lists a number of as yet unresolved issues in the area of technical and logistic requirements and the field tests initiated by DGMK for their resolution. The results of these tests will be described in the follow-up report 616-2.