- June 2022: University of Ioannina, Ioannina, Greece.
- May 2022: Universita Ca' Foscari Venezia, Venice, Italy.
- February - April 2022: University of Ioannina, Ioannina, Greece.
- November - December 2021: Laboratoire d’Informatique et de Systèmes Marseille, France.
- October - November 2021: University of Ioannina, Ioannina, Greece.
- September 2019: Universita Ca' Foscari Venezia, Venice, Italy.
- December 2017: Universita Ca' Foscari Venezia, Venice, Italy.
- June 2017: Laboratoire d’Informatique Fondamentale de Marseille, Marseille, France.
- October 2015: Carleton University, Ottawa, Canada.
- October 2013: Universita Ca' Foscari Venezia, Venice, Italy.
- March 2013: Project COATI, INRIA, Sophia-Antipolis, France.
- November 2011: Laboratoire d'Informatique Fondamentale de Marseille, Marseille, France.
- October 2011: Slovak Academy of Sciences, Bratislava, Slovakia.
- December 2010: Foundation for Research and Technology - Hellas (FORTH), Heraklion, Crete Island.
- November 2010: Laboratoire d'Informatique Fondamentale de Marseille, Marseille, France.
- August 2010: McMaster University, Hamilton, Canada.
- August 2010: Carleton University, Ottawa, Canada.
- March 2010: McMaster University, Hamilton, Canada.
- February 2010: Carleton University, Ottawa, Canada.
- February 2009: Comenius University, Bratislava, Slovakia.
- February 2006: Carleton University, Ottawa, Canada.
- April - May 2005: Carleton University, Ottawa, Canada. (talk abstract)
- November 2004: Project MASCOTTE, INRIA, Sophia – Antipolis, France.