This book constitutes the refereed proceedings of the 6th International Conference on Formal Modeling and Analysis of Timed Systems, FORMATS 2008, held in Saint Malo, France, September 2008. The 17 revised full papers presented together with 3 invited talks were carefully reviewed and selected from 37 submissions. The papers are organized in topical sections on extensions of timed automata and semantics; timed games and logic; case studies; model-checking of probabilistic systems; verification and test; timed petri nets.