Proceedings of COMMA 2020. The investigation of computational models of argument is a rich and fascinating interdisciplinary research field with two ultimate aims the theoretical goal of understanding argumentation as a cognitive phenomenon by modeling it in computer programs, and the practical goal of supporting the development of computer-based systems able to engage in argumentation-related activities with human users or among themselves. The biennial International Conferences on Computational Models of Argument COMMA provide a dedicated forum for the presentation and discussion of the latest advancements in the field, and cover both