This volume of the Lecture Notes in Computer Science series publishes the set of papers accepted for the ICQT 2006 workshop, i.e., the 5th International Workshop on Internet Charging and QoS Technology (ICQT), which was collocated with ACM SIGMETRICS. These events took place in St. Malo, France and were hosted by the IUT (Institut Universitaire Technologique) of St. Malo. QoS-guaranteed services enable a huge variety of prosperous business models, and the need for viable models and pricing schemes is urgent. The resulting combination of technical and economic perspectives drives many relevant research topics for application developers, business architects, network providers, service providers, and customers. Especially the identification of novel service charging solutions, the investigation and evaluation of their technical feasibility, and the consolidation of technical and economic mechanisms for enabling a fast, guaranteed, and efficient charging of services is of fundamental importance for the future evolution of the Internet, and as such the central focus of the international ICQT workshop series. This year’s ICQT constituted the 5th vivid workshop on Internet economics and charging technology, which initially took place in 2001 in Vienna, Austria within the framework of the Annual Meeting of the German Society for Computer Science (GI) and the Austrian Computer Society, and which was collocated in 2002 with the QofIS 2002 workshop in Zürich, Switzerland, in 2003 with the NGC 2003 workshop in Munich, Germany, and in 2004 again with QofIS 2004 in Barcelona, Spain.