This report describes the development in 2013 within the project Electronic Warfare Duel Simulation, a research and development project aimed at supporting the Swedish Armed Forces in the development, use, and setting of requirements of electronic warfare systems and their overall capabilities. During 2013, the second year of the project, efforts were focused on further improvements and developments of the Electronic Warfare Simulation Model framework (EWSim). EWSim is a distributed simulation and assessment system for electronic warfare developed within previous projects at FOI. Several improvements have been made to the EWSim framework:  The architecture has been extended with a plugin system for models created using the MATLAB/Simulink modeling and simulation tools. This allows for integration of several detailed models of weapons systems in larger scenarios.  A Gantt-tool for improved editing of events scheduled to occur over time.  New models for missiles with radar and electro-optical (EO) guidance.  New library based models for countermeasures against radar based threats.  Custom feature enhancements before and after support to exercises.. Further activities include support for Operational Evaluation (OPEVAL) for Helicopter 16 (Blackhawk), collaboration with the R&D project VMS Marin Miljö, and demonstrations of EWSim as part of courses given by FOI. Support has also been provided to the Swedish Armed Forces through participation during exercises at Ledningsregementet (Command and Control) and at the Armed Forces Headquarters. The project will continue with studies on how to use standardized methods for assessment and evaluation of electronic warfare efforts, and perform further development of radar, radio, and electro-optical (EO) simulation systems. Radar modeling will be improved by addition of multipath propagation, and the chaff model will be extended to handle doppler bandwidth. Models of anti-ship missiles using radar and EO guidance will be completed. A demonstration at the end of the project is planned to showcase tools and methodology for electronic warfare assessments, which could be useful for the development of combat style and tactics in preparation for and during future electronic warfare efforts. As a result of the activities during 2013 the project is progressing as planned toward the set project goals.