This volume contains the proceedings of FORMATS 2005, the Third Inter- tional Conference on Formal Modelling and Analysis of Timed Systems, held in Uppsala, Sweden, September 26-28, 2005, in conjunction with ARTIST2 s- mer school, September 29-October 2, 2005, on Component Modelling, Testing and Veri?cation, and Static Analysis of Embedded Systems. FORMATS is an annual workshop series initiated in 2003. It is dedicated to the advancement of formaltheories,techniquesandsoftwaretoolsformodellingandanalysisoftimed systems. FORMATS 2003 wasassociatedto CONCUR 2003(International C- ference on Concurrency Theory), held in Marseilles, France. FORMATS 2004 was organized in conjunction with FTRTFT (Formal Techniques in Real-Time and Fault Tolerant Systems), Grenoble, France. This year, FORMATS received 43 submissions out of which 19 papers were selected for presentation by the ProgramCommittee. Each of the submitted - pers has been reviewed by at least three PC members and their sub-reviewers. The scienti?c program of FORMATS 2005 contained three invited talks: Lothar Thiele(ModularPerformanceAnalysisofDistributedEmbeddedSystems),Karl- ? Erik Arz' en (Timing Analysis and Simulation Tools for Real-Time Control) and Parosh Abdulla (Veri?cation of Parameterised Timed Systems). The 19 - lected contributions cover work on semantics and modelling of timed systems, formalisms for modelling and veri?cation including timed automata, hybrid automata, and timed Petri nets, games for veri?cation and synthesis, mod- checking, case studies and issues related to implementation, security and perf- mance analysis.