Artificial intelligence (AI) is a dynamic field that is constantly expanding into new application areas, discovering new research challenges and facilitating the devel- ment of innovative products. Today's information overload and rapid technological advancement raise needs for effective management of the complexity and heteroge- ity of knowledge, for intelligent and adaptable man-machine interfaces and for pr- ucts and applications that can learn and take decisions by themselves. Although the mystery of human-level intelligence has just started to be uncovered in various int- disciplinary fields, AI is inspired by the respective scientific areas to explore certain theories and models that will provide the methods and techniques to design and - velop human-centered applications that address the above-mentioned needs. This volume contains papers selected for presentation at the 5th Hellenic Conference on Artificial Intelligence (SETN 2008), the official meeting of the Hellenic Society for Artificial Intelligence (EETN). Previous conferences were held at the University of Piraeus (1996), at the Aristotle University of Thessaloniki (2002), at the University of the Aegean (2004) and at the Institute of Computer Science at FORTH (Foundation for Research and Technology - Hellas) and the University of Crete (2006).